
Class TJ lAl 
Book. ■ B4 

COPyRIGHT DEPOSIT. 



THE 

SLIDE-VALVE AND ITS 
FUNCTIONS 



SPECIAL REFERENCE TO MODERN PRACTICE 



UNITED STATES 



WITH 90 DIAGRAMS AND ILLUSTRATIONS 



JULIUS BEGTRUP, M. E. 




NEW YORK 
D. VAN NOSTRAND COMPANY 

LONDON 

E. & F. N. SPON, Limited., 125 Strand 

1902 



THE LIBRARY OF 
0ONCRES8, 

■^■•vr) CoWbt) ReCSIVEO 

OCT. <i^ 1902 

CnPVBiQHT ENTRY 

O'laSS Ou XXo. Ho. 
CX>PY B. 



Copyright, 1902, 

BY 

D. VAN NOSTRAND COMPANY. 



f " 'C^ CC 






TYPOGRAPHY BY C. J. PKTERS & SON,! 

BOSTON, MASS., U. S. A. ^^^^ 




PREFACE. 



The Slide- Valve has been called the heart of the steam en- 
gine, and the simile is not badly chosen ; for the valve is a dis- 
tinct and vital part of the engine, controHing and regulating the 
circulation of its life-fluid in a manner not entirely unlike that 
of a living heart. It is the office of the slide-valve to direct the 
motion and action of this subtile and expensive fluid to best ad- 
vantage and without waste, so as to make the engine an effective 
and economical motor. 

As the valve must be designed so as to effect an economical 
steam distribution in the cylinder, it has attained a peculiar sig- 
nificance in scientific steam engine construction; but durability 
and permanency of form are requirements not less imperative, 
and they involve constructive problems of a different order. In 
recognition of this fact an attempt has been made in this work 
to treat the subject with due regard to the various requirements 
of modern practice. The fundamental principles are fully ex- 
plained, and are illustrated by new graphical methods, and a 
number of special valve constructions are described and analyzed, 
in order to exhibit in a comprehensive manner how the exacting 
conditions of higher steam pressure and higher speed have been 
met by modern engine-builders. 

An endeavor has been made to present the subject-matter 
of this book in a condensed form, as being best adapted to the 
requirements of practical men, and the author has in this re- 
spect followed the suggestions of an extensive personal experi- 
ence. 



IV PREFA CE. 

The information is presented in more or less explanatory 
form, which is necessary in order to preserve its scope and gen- 
eral character by the absence of a multiplicity of details ; but 
lengthy explanations are studiously avoided, for it is the author's 
opinion that practical knowledge — which is the more complete 
knowledge — cannot be imparted by the use of many words. 
Nothing is fully comprehended before the learner can follow the 
thoughts of the teacher, but he must be allowed to learn this 
in his own way, or by his own efforts, if the acquired knowledge 
'is to be of any actual use. All the book really can accomplish 
is to start the reader thinking in the right direction, which often 
may be done by a few carefully selected words. 

Both verbal and graphical demonstrations are used, that one 
form may supplement the other. The verbal treatment is the 
broader, but the graphical representation is indispensable as an 
illustrative and explanatory supplement, and as far as the valve 
motion is concerned, it is the only method practiced by those 
who build engines, or make the drawings from which they are 
built. Further, the graphical representation has the advantage 
that it presents a number of associated facts in one frame, as it 
were ; and it may, therefore, eventually lead to those broad con- 
ceptions which are of so great practical utility, and which the 
best verbal exposition sometimes may fail to disclose. 

The valve-diagrams presented in this book have been used 
for the; last ten years, on many different occasions, and they 
have given more general satisfaction than others which are 
better known ; and the reader will doubtless share this opinion, 
if the methods here used are accorded a fair trial. 

Comparatively few letters of reference are used in the text, 
and it is believed that this will make it easier to follow the dem- 
onstrations. 

J. BEGTRUP. 
Jersey City, N. J., January, 1902. 



TABLE OF CONTENTS. 



CHAPTER I. 

THE COMMON SLIDE-VALVE. 

Page 

Introductory Remarks i 

The Common D-Valve . . ; 2 

Simplest Form of Slide-Valve 4 

The Valve-Motion in Relation to the Piston-Motion .... 9 

Valves Without Lap ii 

The Primitive Valve-Diagram 12 

Sweet's Valve-Diagram 14 

Variable Valve Travel 15 

Limitations of the Combination Valvk 16 

Steam-Ports 18 

Port-Opening 19 

Valve Dimensions , . . . 20 

Valve Diagram for Shifting-Eccentric Engines 21 

Variation in Port-Opening 24 

Notes About Lead 25 

Compression 27 

The Motion of Locomotive Valves ....■%.,. 28 

Multiporting 31 

Setting the Engine on Dead Centers 32 

CHAPTER n. 

improved slide-valves. 

The Double-Ported Marine Slide-Valve 34 

The Allen Locomotive Valve 35 

The Straight-Line Balanced Valve 36 

Variations of the Straight-Line Valve 38 

The McEvven Valve 39 

The Ball Telescopic Valve 41 

Balancing a Common D-Valve 42 

The Richardson Balanced Valve 44 

v 



VI TABLE OF CONTENTS. 

Page 

The Thomas Balance 44 

Piston-Valves 46 

Valves of the " Ideal Engine " 47 

The Westinghouse Standard Valve 49 

Valves on Compound Engines 50 

The Westinghouse Compound Valve 53 

The Vauclain Valve 54 

The Allfree Valve-Gear 57 



CHAPTER III. 

foir-valve systems. 

Introductory Remarks 61 

Corliss Valves 62 

JLlMITATIONS of THE CoRLISS GeAR 65 

The Single-Eccentric Valve Dl\gram 67 

Two Eccentrics 69 

Corliss Valve Dimensions 71 

Directions for Setting the Valve-Gear 72 

Valves of the Porter-Allen Engine 72 

Gridiron Valves 75 

The Hill Valves 76 

The Wheelock Valves 78 

CHAPTER IV. 
independent cut-off. 

Introductory Remarks 80 

The Cut-Off Valve on a Stationary Valve-Seat 81 

The Cut-Off Valve on the Back of the Main Valve .... 83 

Fundamental Principles 83 

The Meyer Cut-Off 85 

The Meyer Cut-Off Diagram 86 

Limitations of the Meyer Cut-Off 89 

The Rider Cut-Off Valve 89 

Cut-Off Varied by Rotating Eccentric on Shaft 90 

Gridiron Valves With Independent Cut-Off 96 

Begtrup's Eccentric 97 

Cut-Off Valve With Constant Travel on Main Valve .... 99 

The Buckeye Valve-Gear 102 

Piston-Valves With Independent Cut-Off 105 

Cut-Off Valve Worked by Means of a Link 106 

Independent Cut-Off on Four- Valve Engines 108 



TABLE OF CONTENTS. vii 

Page 

The McIntosh & Seymour Valves io8 

Valves of the Russell Engines lio 

The Buckeye Vibrating Cut-Off iii 



CHAPTER V. 

THE slide-valve ON PUMPS. 

Blake 117 

Dean Brothers 119 

Knowles 121 

Davidson 121 

Cameron 123 

Worthington •. . . . 124 

CHAPTER VI. 

angularity of connecting-rod and eccentric-rod. 

The Angular Motion of the Connecting-Rod 128 

The Angular Motion of the Eccentric-Rod 132 

Steam- and Exhaust-Laps 134 

Equalizing both Lead and Cut-Off 134 

The Inclined Rocker for Shifting-Eccentric Engines .... 136 

Equalizing the Lead on Shifting-Eccentric Emgines . . . . 137 

Unequal Laps on Variable Cut-Off Engines 139 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



CHAPTER I. 

THE COMMON SLIDE-VALVE. 

INTRODUCTORY REMARKS. 

The term << slide-valve ** is applied to flat-faced valves having 
a continuous reciprocating sliding motion, whereby steam is 
alternately admitted to and exhausted from a cylinder ; and this 
term will also apply to similar parts of gas, air, and water 
engines and pumps. The steam engine slide-valve and some 
typical pump valves will be considered here. 

The sliding surfaces may be cylindrical, and this does not 
affect the principles of the valve motion ; but in such case dif- 
ferent names are used, as piston-valve, Corliss-valve, semi-rotary 
or oscillating valve, etc. These valves are only modifications 
of the original slide-valve, and they will be included as such here. 

Slide-valves, of whatever design, can easily be referred to 
and compared with the common D-valve, their functional prop- 
erties, in all cases, being closely related. But the D-valve — 
so called because in section slightly similar to the letter D — is 
not the simplest slide-valve, per se ; and in order to fully under- 
stand the principles and master the analysis of the subject, it 
is advisable to commence with a careful study of the simplest 
elementary form. 

By thus taking up the elements of the subject, or going to 
the bottom of it, as it were, the consequent study of more or 

1 



2 THE SLIDE-VALVE AND ITS FUNCTIONS. 

less elaborate forms and combinations will be greatly facilitated ; 
and such a course may lead to broad and independent views, so 
essential to successful and progressive engineering. 

The diagrams presented in this chapter are not supposed to 
represent actual practice. They are only here to illustrate and 
explain the text, and to give graphical directions for laying out 
the essential parts of valve and gear, and no attempt is made to 
show details. Some of the sketches are purposely out of pro- 
portion, for otherwise almost unlimited space would be required, 
or else clearness and distinctness of the principal parts would be 
sacrificed ; and it can hardly be considered a serious defect, for 
some imagination is a prerequisite in constructive engineering, 
for which there is no substitute. 



THE COMMON D-VALVE. 

Fig. I shows the valve in its central position and part of 
the cylinder. By moving the valve to the right steam is 

exhausted from the right 
hand side of the cylinder 
and admitted to the left 
hand side ; and by moving 
it to the left steam is ex- 
hausted from the left hand 
side, and admitted to the 
right hand side. Steam is 
admitted past the outer edges 
^^* '• of the valve, and the exhaust 

escapes past the inner edges into the exhaust-cavity, and from 
thence to the exhaust-pipe (not shown). 

The flat surface on which the valve slides is called the valve 
face of the cylinder or the valve-seat, and the corresponding 
surface of the valve is the face of the valve. The orifices of 
steam -passages, covered by the face of the valve, are the steam- 




THE COMMON SLIDE-VALVE. 6 

ports, and the central opening in the cylinder casting is called 
the exhaust-port. 

The conventional use of this term is somewhat unfortunate, 
for, as the exhaust from the cylinder passes out through the 
same ports through which steam is admitted, these ports are 
also entitled to be named exhaust-ports. True, the terms steam 
and exhaust signify here only different conditions of the steam, 
but the name '' exhaust-port " for the middle opening conveys 
unconsciously the impression that the two exterior ports are for 
steam only, and the central port is for the exhaust. Besides, 
the name port is too dignified in this connection, where it only 
means a hole or opening through which the exhaust escapes 
after it has left the steam-port, and no particular importance 
attaches to this hole ; it can be of any shape and size, provided 
it is big enough ; in fact, it hardly needs a special name. 

The steam-ports, on the other hand, are essential and char- 
acteristic components of the valve-face, for in conjunction with 
the valve, they regulate the steam distribution in the cylinder, 
and their location and dimensions require careful consideration. 
Engines having separate exhaust-valves have also separate 
exhaust-ports, but these bear no relation to the "exhaust-port," 
so called, of the common D-valve. The force of this argument 
will become apparent later on. 

That part of the face of the valve which overlaps the out- 
side edge of the steam-port, when the valve. Fig. i, is in its 
central position, is called steam-lap, and the over-lapping of the 
inside edges is called exhaust-lap. The terms " inside " and 
"outside " lap are often used, but are not to be recommended, 
for many valves have steam-lap on the inside and exhaust-lap on 
the outside. Valves are often constructed without exhaust -lap, 
and occasionally the exhaust-edge of the valve does not reach 
to the port-edge, in which case the face of the valve does not 
entirely cover the ports in its central position, and the un- 
covered part is then referred to as negative exhaust-lap or 



4 THE SLIDE-VALVE AND ITS FUNCTIONS. . 

exhaust clearance. If not otherwise specified, lap means steam- 
lap. The two partitions which separate the steam-ports from 
the exhaust-opening are named bridges. 

It is proper to study the slide-valve as it relates to the 
action of steam on one side of the piston only ; for in a double- 
acting cylinder, being, as it were, a combination of two single- 
acting cylinders, the action on one side of the piston is 
practically an exact repetition of that on the other side ; and 
the D-valve can be divided into two equal halves, each of which 
will take care of the steam on one side of the piston ; and in 
order to place the back pressure in its proper relation to the 
forward stroke, it is only necessary to consider the exhaust- 
action in reversed order. 

The duty of the shde-v^alv£, broadly speaking, is to admit 
steam during the forward stroke and exhaust it during the 
return stroke, and which includes expansion and compression. 

The majority of engines are double-acting ; that is, steam is 
admitted alternately on both sides of the piston, and the com- 
mon slide-valve is charged with the fourfold duty of admitting 
and releasing steam at both ends of the cylinder ; and we may 
conceive this being attained by a unification of four valves in 
one body. The regularly alternating periods of admission and 
exhaust, and the symmetrical arrangement of steam-ports admit 
of a single valve being used. 

SIMPLEST FORM OF SLIDE-VALVE. 

Fig. 2 represents a slide-valve, whose only duty is to open and 
close for admission of steam to one side of the piston. When it 
is moved to the right, a sufficient distance, it uncovers part of 
the port and admits steam to the. cylinder, and by its retrograde 
motion the port is closed again. It controls the admission of 
steam only, and there will have to be another valve to open and 
close for the exhaust ; and in case of a double-acting engine two 
such pairs, or four valves in all, would be needed. 



THE COMMON SLIDE-VALVE. 



The reciprocating motion of slide-valves is generally pro- 
duced by eccentrics attached to the crank shaft of the engine, 
and an eccentric - — being nothing but an enlarged crank-pin — 



.^^r-Jo~^ 




Fig. 2. 



^HC^o 




*-<!t.OSE0 — *Ji)p 



Fig. 3. 



^/:$ 




Fig. 4. 



?.io 




Fig. 5. 

is in the annexed diagrams represented by a small crank, or 
arm, E, and which communicates motion to the valve through 
a rod, as indicated. The diameter of the circle described by 



6 THE SLIDE-VALVE AND ITS FUNCTIONS. 

the center of the eccentric is called the throw of the eccen- 
tric, and it represents here the full stjoke or travel of the 
valve. 

According to this definition the throw of an eccentric is 
twice its eccentricity or radius ; but, as the throw of a crank 
means the distance from center of shaft to center of crank-pin, 
it ought to mean the same when speaking of an eccentric. 
However, rhetoric is not cultivated in the shop or engine room, 
and when they talk about the throw of an eccentric it is well 
understood what it means. 

For convenient representation in a limited space, the dis- 
tance between eccentric and valve is made short in the diagram, 
which makes the angularity of the eccentric-rod appear ab- 
normal. In ordinary stationary engines this angularity is 
always very slight, and its effect on the valve motion may be 
ignored ; and for this reason we may assume the eccentric-rod 
parallel with its medial-line of action, as also would be the case 
if we assume an eccentric-rod of infinite length.* 

Fig. 3 shows the valve in the position where it commences 
to open the steam-port. Edge A of the valve and edge B of 
the port are now '■'■ line and line," and by continued turning 
of the eccentric in the direction shown by the arrow, these 
edges will separate, leaving an increasing opening for the pas- 
sage of steam, till the eccentric has reached the extreme of its 
throw, when by further turning it will push the valve back 
towards edge B ; and when the eccentric is in position 4, verti- 
cally opposite position i, the port is closed again. 

It should be observed that we are here only considering 
one edge of the valve and one edge of the steam-port ; other re- 
lations of port and valve being for the present quite immaterial. 
These edges come together twice during each revolution of the 
eccentric, when it is at the vertically opposite points i and 4, 

* The actual effect produced by the angular motion of the eccentric-rod is explained in the 
last chapter of the book. 



THE COMMON SLIDE-VALVE. 7 

and the valve, therefore, opens and closes the port once during 
each revolution. 

If arc 1-4 represents the period during which the port is 
open, arc 4-1 will represent the period during which it is closed. 
The greatest port opening is equal to the distance G-3, and for 
any position of the eccentric, the corresponding port opening 
can be measured horizontally on the shaded segment. When 
the eccentric is at << half throw,*' at point 10, the valve is in 
the position shown in Fig. 2, and the amount it overreaches the 
port in this position is the << lap,** and which is equal to the 
distance L. Thus the length of the period during which steam 
is admitted depends on the amount of lap, for the valve must 
move from its middle position a distance equal to the lap before 
it uncovers the steam-port, and it is evident, that the longer the 
period during which the port is closed the shorter must be the 
period during which it is open. A correct idea of this relation- 
ship can be had by an inspection of the figure, which clearly 
shows how an increase or diminution of distance L affects the 
period of steam admission. 

Comparing the valve here described with that shown in Fig. 
I it will be seen, that by cutting off one-half of the latter and 
filling up the exhaust-cavity, we have a valve very similar to 
that shown in Fig. 2, and operating in exactly the same manner. 
It will also readily be seen that a valve like that shown in Fig. 
2, working in a separate chamber, could be made to open and 
close an exhaust-port in much the same manner as the steam- 
valve controls the admission of steam or as one of the inner 
edges of the D-valve, Fig. i, controls the exhaust, and that the 
period of exhaust for each turn of the eccentric would depend 
on an exhaust-lap corresponding to the steam -lap in Fig 2 or 
the exhaust-lap in Fig i. 

Fig. 5 shows an exhaust-valve and its eccentric at half 
throw ; the main difference between this valve and the steam- 
valve. Fig. 2, being that in Fig. 5 the valve is turned end for 



8 THE SLIDE-VALVE AND ITS FUNCTIONS. 

end and has a smaller lap, which makes the period of exhaust 
longer than the period of admission. It would also be necessary 
to provide means for holding this valve to its seat, which is not 
shown. 

The period of exhaust is represented by the arc of the 
shaded segment. Fig. 5. If the exhaust eccentric is fixed on 
the shaft in the same position as the steam eccentric, the 
period of exhaust will, in a manner, be diametrically opposite 
the period of admission ; that is, if we imagine the period of 
revolution represented by a circle. Under such conditions, it is 
evident that all four valves for a double acting engine might be 
driven by one eccentric ; and by uniting the four valves in one 
body, and by providing an exhaust cavity to keep the exhaust 
separate from the live steam, we arrive at the construction 
shown in Fig. i. 

It should be noted again, that here the exhaust passes 
through a port which also serves for admission of steam, and 
that steam passes over the outer edge of this port on its way 
to the cylinder, and is exhausted from the cylinder over the 
opposite edge, and that the steam- and exhaust-lap, therefore, 
extend in opposite directions, as on the separate valves Figs. 2. 
and 5. Each operation of this valve, therefore, depends on the 
relative position of two individual edges, just as does each 
operation of the simple valves referred to ; and thus is estab- 
lished the proposition that such simple valves are, in a sense, 
integral parts of the D-valve, or, in other words, the D-valve is 
equivalent to four simple valves driven by one eccentric. 

Let the circle in Fig. 6, p. 12, represent the path of the 
center of the eccentric, and arcs 1-4 and 6-9 represent steam 
and exhaust periods respectively, during one revolution of the 
eccentric, for the left half of the D-valve, and the left side of 
the piston. It is here observable that the greatest steam and 
exhaust openings occur wjien the valve is at the two extremes 
of its travel, that is, at diametrically opposite points of the 



THE COMMON SLIDE-VALVE. 9 

period of revolution; that any opening of the port can be 
measured horizontally on the segments ; that if there be no 
exhaust lap, the exhaust period will cover one-half revolution ; 
and that lap plus port-opening equals half travel of valve. 

THE VALVE-MOTION IN RELATION TO THE PISTON-MOTION. 

The main object of the discussion so far has been to es- 
tablish a clear conception of the simple relationship which 
exists between laps and periods of admission and exhaust. The 
next subject for consideration is the relation of these periods to 
the motion of the piston in the cylinder, which includes deter- 
mination of the position of the eccentric relative to the crank. 
It has been shown how these periods may be lengthened or 
shortened by changing the laps of the valve ; and any one of 
them can evidently be made to coincide with any period of the 
piston-stroke by fixing the eccentric in a suitable position on the 
crank-shaft. 

First : Where should the valve be when the piston is at the 
end of the cylinder and commencing its forward stroke .'' As 
the port must open at or near the beginning of the piston- 
stroke, when the crank is on its first << dead center/' and as the 
period of admission occurs during the opposite half-revolution of 
the eccentric, and must be considerably less than one-half period 
of revolution, it follows that the eccentric must be past the 
middle of its throw, or more than one-quarter of a revolution 
ahead of the crank. Let C, Fig. 3, represent the crank when 
the valve is at the point of admitting steam, at i, then consider- 
ing that eccentric and crank are moving together with the crank 
shaft, it is clear that when the crank has arrived at the end of 
its return stroke, at C, Fig. 4, the eccentric has advanced the 
same angular distance, from position i to 2, and there will be 
a small opening between the valve and the port-edge, as shown ; 
and during this short interval steam enters the cylinder in ad- 



10 THE SLIDE-VALVE AND ITS FUNCTIONS. 

vance of the piston. This initial port opening is called lead or 
sometimes steam-lead, in contradistinction from exhaust-lead, 
which means the opening for exhaust at commencement of the 
return stroke. Steam-lead is usually supposed beneficial, and 
the desirability of exhaust-lead is unquestionable. Lead is in- 
creased by turning the eccentric forward on the shaft, and is 
diminished by turning it backward. 

Sometimes, under certain conditions, the port opens after 
the forward stroke has commenced, and in such case the ex- 
pression << negative-lead'* may be used, to indicate that the 
valve overlaps the steam -port to a certain extent at the com- 
mencement of the stroke. 

Let the position of the eccentric at the beginning of the 
stroke be at 2, Pig. 4 ; then period of admission from the time 
the piston starts on its forward stroke is represented by arc 
2-4, which obviously always should be considerably less than 
the period of one-half revolution in order to provide for expan- 
sion of the steam. The angle 10-2 has been named the angle 
of advance, but, thus should be named the angle between the 
crank arm and eccentric arm ; for it represents how much the 
eccentric actually is in advance of the crank. Any other des- 
ignation is confusing, and there is no valid reason for any other 
use of this term. If there ever was a good reason for it, it 
does not exist now. In this book, the <* angle of advance" 
means the angular advance of the eccentric relative to the crank, 
as represented by angle 8-2, Fig. 4 and 6. 

When, by continued turning of the shaft, the eccentric 
reaches position 4, the admission of steam to the cylinder is 
cut off. Where will the piston then be } Mark off the angle of 
advance from point 4 in a reverse direction, and a radial line 
intersecting the crank-circle marks the location of the crank- 
pin, and its horizontal projection will indicate approximately the 
position of the piston in the cylinder when the admission of 
steam is cut off and expansion commences. The exact location 



HIE COMMON SLIDE-VALVE. 11 

of this point — the point of cut-off — is sometimes required, 
and the angularity of the connecting-rod must then be taken 
into account. (See last chapter.) 

As steam always is admitted at a point very near the com- 
mencement of the stroke, the period of admission must be made 
shorter or longer according as an earlier or later "cut-off" is 
required. This can be effected by lengthening or shortening 
the steam-lap ; but as the point of admission is fixed near the 
commencement of the stroke, the period as a whole must occur 
earlier or later according to the location of the point of cut-off, 
and the angle of advance must be changed accordingly — which 
will become quite clear by an inspection of Fig. 4. Thus is 
established the important rule : Period of admission is shortened 
by increasing the lap and the angle of advance, and is lengthened 
by diminishing the lap and angle of advance. Also mark : 
that all periods of steam, distribution occur earlier or later in the 
stroke, according as the eccentric is turned ahead or back on the 
shaft. 

VALVES WITHOUT LAP. 

Valves have been used without steam- and exhaust-lap at 
a time when the gain by expansion was not fully recognized 
and compression of exhaust had no significance. When such 
valves have their eccentrics at right angles to the crank, the 
points of admission and release of the steam occur when the 
crank is on its " dead center " ; but the eccentric was presum- 
ably moved forward some to give the valve-lead. Such valves 
are not used now, and they may be classed with historical curi- 
osities. In treatises on the steam-engine this lap-less construc- 
tion is usually discussed at length as an introductory to a chapter 
on slide-valves, though the discussion of this special and obsolete 
construction seems hardly profitable, and it is not conducive to 
a broad, practical conception of the general subject. 



12 



THE SLIDE-VALVE AND ITS FUNCTIONS, 



THE PRIMITIVE VALVE-DIAGRAM. 



Fig. 6 is a combination of diagrams 4 and 5, and it represents 
a simple D-valve diagram. The crank is supposed to be at its 
dead center, or at the extremity of its throw, at the commence- 




Fig. 6. 

ment of the forward stroke, and significant positions of the valve 
during one revolution of the crank are indicated diagram mat ically 
to the left. The various positions of the eccentric are marked 
on the eccentric-circle in the following order. 

1. Point of admission, just before end of return stroke. 

2. Lead at commencement of forward stroke. 

3. Extreme throw of valve, port "vvide open. 

4. Steam is cut off, expansion commences. 

5. Valve in central position. 

6. Point of release. 

7. Exhaust-lead, at commencement of return stroke. 
■ 8. Extreme throw of valve, exhaust wide open. 

9. Exhaust-closure ; compression commences. 
10. Valve in central position. 



THE COMMON SLIDE-VALVE. IS 

This diagram exhibits in a natural manner all that is required 
for a full understanding of the functions and principles of con- 
struction of a common slide-valve, and from it the position of 
the valve relatively to the ports, at any point of the stroke, can 
readily be ascertained by marking off the angle of advance on 
the eccentric-circle. Note that in this diagram the eccentric- 
arm is supposed to be moved in unison with the crank-arm, as 
it does move in reality. 

The simple and direct relationship between eccentric and 
valve motion, as here assumed, is often changed by the interven- 
tion of a special valve-gear ; but the resolution of such cases 
presents no special difficulty. Usually the valve-motion is 
assumed, and the throw and position of the eccentric are then 
deduced from the design of the valve gear. 

It should be particularly noted that the valve-end of the 
eccentric-rod must be in the same position when the valve opens 
and closes the port, and that, therefore, each pair of points, 1-4, 
and 6-9, which mark the beginning and end of the admission and 
the exhaust period respectively, must be equally distant from 
a certain point which marks the location of the eccentric-rod pin 
when the valve and port edges come together, and that, there- 
fore, if the valve-end of the eccentric-rod travels in a straight 
line, which extended passes through the center of the crank- 
shaft, chords 1-4 and 6-9 must be parallel. A slight devia- 
tion from this ' direction, caused by the swing of an ordinary 
rocker arm, is of so little consequence that it may be entirely 
ignored.* 

The foregoing discussion presents the fundamental- princi- 
ples which must govern the construction of slide-valves of any 
description, and it will serve as an introduction to the study of 
other forms of valves. 

* The general effect of a rocker motion in other directions than the center of the shaft is 
discussed in the last chapter of the book. 



14 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



SWEET S VALVE-DIAGRAM. 

In Fig. 6 the various positions of the valve relative to the 
port during a complete revolution of the eccentric are indicated 
by the eccentric-arm, as a pointer ; but if the circular figure be 
turned backwards through an angle equal to the angular advance 
of the eccentric, without disturbing the crank, all the points in 
the circumference will be placed in the same position relative tO' 




the crank-arm as they now occupy relative to the eccentric-arm ; 
and if then the crank-arm, or its center line, be moved into any 
new position, the corfesponding position of the valve will appear 
directly from the marks in the circumference of the circle. A 
valve-diagram thus modified is shown in Fig. 7. Note that valve 
measurements and port-openings are taken at right angles to the 
oblique lines, and that these lines must be parallel. For con- 



THE COMMON SLIDE-VALVE. 15 

venience, the eccentric-circle is drawn full size, and the crank- 
circle is reduced, so as to make both circles appear of same size. 

From this circular diagram a theoretical indicator diagram 
can readily be constructed, as shown, which adds greatly to its 
usefulness ; for to many engineers the indicator diagram exhibits 
and explains, at a single glance, all the peculiarities of the steam 
distribution in the cylinder, and it sometimes contains a whole 
story in graphic language. 

This valve-diagram, slightly modified, was first published by 
Professor John E. Sweet in the American Machinist of August 
30, 1884, and I know no reason why it should not be named the 
*' Sweet valve-diagram/* No attempt should be made to use 
the same diagram to indicate different valve proportions or set- 
tings, for it makes it confusing to the eye, and it is entirely un- 
necessary, as half a dozen such diagrams can be drawn in "■ less 
than no time." 

In order that the opening and closing of the ports may 
take place at the proper moments during the forward stroke 
and return stroke respectively, the eccentric must be set at a 
certain angle in advance of the crank ; and its location depends, 
therefore, on the direction in which the crank turns, though the 
angle of advance is the same in either case. A reversal of the 
crank motion would change the valve diagram, only so far as all 
- points above the center line would occupy corresponding posi- 
tions below it, and vice versa, — as if the diagram were turned 
around its horizontal diameter. 

VARIABLE VALVE TRAVEL. 

A glance at the diagram shows that the longer the lap the 
shorter the period of admission, and the smaller the port open- 
ing ; but it should also be noted that the length of periods of 
admission and exhaust depends absolutely on the relation be- 
tween lap and travel of valve, and that, therefore, shortening 
the travel has the same effect as increasing the lap, so far as 



16 THE SLIDE-VALVE AND ITS FUXCTIONS. 

these periods are concerned ; but shorter travel yields smaller 
openings for admission and release. 

It has been shown how the location of the point of cut-off 
can be changed by changing the lap of the valve and the angu- 
lar advance of the eccentric, and it is evident that this may also 
be done by changing the throw of the eccentric and its angular 
advance, without changing the lap. For instance : by diminish- 
ing the throw the period of admission becomes less, and by ad- 
vancing the eccentric the proper lead is obtained, which will 
become clear by an inspection of diagrams 6 and 7. Improved 
slide-valves are often driven by shiftable eccentrics whose throw 
and angular advance are automatically changed so as to vary the 
point in the stroke where steam is cut off, as, for instance, on 
many high-speed engines ; or the same result is obtained by 
hand adjustment, as on the locomotive. 

LIMITATIONS OF THE COMBINATION VALVE. 

The main limitations of the D valve, or combined steam 
and exhaust valve, as a steam distributer, is due to the fixed 
union of its steam and exhaust edges, as when separate steam 
and exhaust valves are driven by means of one rod. Maximum 
steam and exhaust opening must occur when the eccentric is at 
either end of its stroke, just in the middle of periods of admis- 
sion and exhaust respectively ; and there being only one eccen- 
tric, this must occur at diametrically opposite points in the period 
of revolution. If, for instance, the admission period is fixed, 
the exhaust period cannot be arbitrarily changed ; for, the eccen- 
tric being fixed on the shaft to suit the admission period, we 
can only vary the exhaust period by varying the exhaust lap, 
but this will give a variation in both directions ; that is, if the 
exhaust opens earlier it will close later, and if it opens later it 
will close earlier. The cycle of contiguous events, as marked 
on the eccentric circle, shows this clearly ; also that an early 
cut-off of the steam in the cylinder is followed by early release 



THE COMMON SLIDE-VALVE. 17 

and early exhaust closure, and consequently by much compres- 
sion of the exhaust. It is therefore quite common practice, 
when not exhausting into a condenser, to omit the exhaust lap. 
Moving the exhaust edge back still farther would probably pve 
too early release. v_ 

It should be noted that the functional restrictions here men- 
tioned are inherent in any combination of a steam and exhaust 
valve conjunctively driven by a single eccentric, because such 
valve-gear must derive all its motions from the eccentric, and 
its alternations must follow closely those of the engine, without 
reference to the nature of the valve-gear. 

The increased compression which follows an early cut-off 
is sometimes considered an unavoidable evil or inherent defect, 
and sometimes a desirable feature or incidental advantage of 
the combination slide-valve, according to existing conditions or 
various theories. 

It should be noted that by an early cut-off the steam open- 
ing is much restricted, and particularly so near the point of 
cut-off, where the steam current is comparatively rapid. The 
most natural remedy would be an increase of the valve travel, 
but in case of an unbalanced valve this would increase the 
unbalanced area and the friction proportionally. When it is 
desired to limit the valve travel, duplicate or supplementary 
steam-ports are sometimes resorted to. The restriction of the 
port-opening, however, is of little consequence, unless the steam 
is cut off very early in the stroke ; and the attendant early re- 
lease is probably the most objectionable feature. Very early 
cut-off is only used in connection with a shif table eccentric or 
with a link-gear ; and the discussion of this case will be resumed 
later. 

The central exhaust cavity of the D-valve removes pressure 
from the front of the valve, and causes it to be held firmly to 
its seat by steam pressure on its back ; but the unbalanced 
pressure is always excessive, and in order to reduce it a 



18 THE SLIDE-VALVE AND ITS FUNCTIONS. 

pressure-balancing device on the back of the valve is often 
resorted to.* 

On long-stroke engines the steam passages become very 
long unless the valve is lengthened correspondingly, and the ex- 
haust passage between the valve and cylinder makes it impossi- 
ble to bring the valve very close to the cylinder-bore ; but these 
objections are only of consequence when it is desired to make 
the steam passages short and direct. Great adaptability, sim- 
plicity, and compactness are characteristics of the common D- 
valve ; and for engines using steam at low or medium pressure 
governed by throttling, it will hardly be superseded. 

STEAM-PORTS. 

When designing slide-valves, one of the first data required 
is the size of steam-ports. No general rule can be given for 
this ; in fact, progressive engineers consider it an unsettled 
matter. Much depends on the piston speed, but there are 
other influential conditions. If it is desired to admit steam 
to the cyHnder under full pressure, larger ports are required 
than if the pressure is to be throttled down ; and if a consider- 
able decrease of speed is permissible under an occasional extra 
heavy load, as, for instance, by hoisting-engines, comparatively 
small ports give entire satisfaction, and are preferable to larger 
ones. The length and shape of steam passage and port may 
have an important bearing on their sectional area, but narrow 
ports are requisite in order to keep the valve motion within 
practical limits. The discovery may still be made that the pas- 
sage, and not the port, is the governing element. The " me- 
chanical instinct " of the engine-builder will make the port 
conform to the passage, but this instinct is not reliable when 
the molecular action of steam is involved. In the writer's per- 
sonal experience, for instance, an abrupt contraction of the port 
to less than half its original size, as shown in Fig. 8, did not 

* See page 42. 




THE COMMON SLIDE-VALVE. 19 

lower the admission-line or raise the exhaust-line on the indica- 
tor-card. This phenomenon is susceptible of a rational expla- 
nation, but mere speculation is not in place here. f 

Incidental experiences seem to prove that the condition of 
the steam, whether wet, dry, or superheated, is 0:^no little 
consequence. Dry steam, being more subtile 
than wet steam, moves easier .or does not adhere 
to the sides, and therefore does not require so 
large ports or passages. ^^S- 8. 

It may safely be assumed, that if the ports and passages are 
large enough to allow the exhaust to pass through without appre- 
ciable back pressure, they are amply large for the entering 
steam, and if the indicator card shows a "good" exhaust-line, 
the ports are large enough, no matter how bad the "steam-line " 
appears. 

For some years past it has been a rule to make the ports of 
high-speed engines large enough to make the mean velocity of 
the steam current 6,000 feet per minute, which for 600 feet 
piston speed makes the port area equal to one-tenth of the 
piston area ; but occasional experiences indicate that, if the pas- 
sages are short, a much smaller area may give perfect satis- 
faction, and the above rule is probably now becoming obsolete. 

The rule here mentioned entirely ignores friction against 
the walls of the passage ; this could be remedied by introducing 
some power of the diameter of the cylinder as a separate factor 
in the formula. The general formula might, for instance, be : 
Velocity of steam, in feet per minute, equals 3,000 times the 
cube root of the diameter in inches. For an 8-inch cylinder this 
would make the mean velocity through the ports 6,000 feet per 
minute, and for a 2 7 -inch cylinder it would make it 9,000 feet. 

PORT-OPENING. 

<< Port-Opening ** means the uncovered part of the port, and it 
should not be confounded with the << port,** which is the orifice 



20 THE SLIDE-VALVE AND ITS FUNCTIONS. 

of the Steam passage. The valve may not open for steam as 
much as the width of the port ; for experience has taught that 
restriction of a steam passage by two sharp edges, within a cer- 
tain Hmit, has very Uttle, if any, effect on the steam current. 
It is known, for instance, that a throttUng-valve of the piston 
type does not have to open but very Httle to allow full pressure 
steam to pass through, and on many automatic cut-off engines, 
the port opening is much restricted without appreciable loss of 
pressure. 

VALVE DIMENSIONS. 

After the travel, point of cut-off, and lead have been deter- 
mined upon, a circular diagram like Fig. 7 may be drawn, and 
this will give the lap and port opening. If a larger port-open- 
ing is desired the lap and travel must be increased proportion- 
ally. A line may be drawn obliquely across the parallel lines 
as shown, so as to give the desired port-opening, and the other 
dimensions will appear at once, correctly proportioned, on the 
same line. By this method the' lead will be increased with the 
port-opening, but the period of preadmission remains unaltered. 
In any case, it is advisable to draw a fresh diagram for any con- 
templated alteration, for the labor it involves is very insignifi- 
cant compared with resulting clearness and simplicity ; and the 
final diagram should be duly labeled and kept as a record for 
future reference. 

After port, travel, steam- and exhaust-lap have been obtained, 
a section of valve and valve-seat may be drawn ; and it should 
be observed that the exhaust after leaving the port is not inter- 
fered with too much by the opposite exhaust edges. On unbal- 
anced valves it is advisable to reduce the exhaust cavity as much 
as possible ; and in that case, the central exhaust opening at the 
extreme of the travel may be reduced to five-eighths of the area 
of the steam-port by overlapping of the valve. 



THE COMMON SLIDE-VALVE. 



21 



VALVE DIAGRAM FOR SHIFTING-ECCENTRIC ENGINES. 

By making the parallel lines in Fig. 7 slant the^ther way, 
as if the figure were turned end for end, we get a ^agram which 
has a certain constructive advantage and also a less desirable 
feature. It becomes a left-hand diagram for a right-hand crank 
motion, as it were ; and the various valve movements, incidental 
to the ■ turning of the crank, must be traced out from right to 
left, while the crank actually turns from left to right. But such 
diagram will present the slanting lines at right angles to the 
eccentric arm, which facihtates its construction for valves with 
variable travel, as used on certain automatic cut-off engines and 
on locomotives and marine engines. 

Fig. 9 shows how to lay out a valve diagram in this manner 
for an engine having two valves driven by separate eccentrics, 
one of which controls the 
steam admission and the 
other controls the exhaust. 
The induction-valve is driven 
by an eccentric of variable 
throw, the center of which is 
supposed movable, relative to 
the crank, on the curved path 
ABC, whereby its throw and 
angular advance are simul- 
taneously changed. Thus, 
when the period of admission 
is shortened by reducing the 
throw, the proper lead is main- 
tained by a corresponding 
angular advance. In the nat- 
ural diagram. Fig. 6, lead is Fig. 9. Sweet's Valve Diagram, 
represented by the horizontal distance of the center of eccentric 
from chord 1-4, and it can readily be reproduced in Fig. 9 in 




'Exh. Ecc 



22 THE SLIDE-VALVE AXD IIS FUXCTIOXS. 

the following manner : With a radius equal to the lap draw a 
circle, as shown, and drop a vertical from center of eccentric ; 
the distance from this to the lap circle is lead. In the present 
case, the lead becomes less as the eccentric advances, and is nil 
at C, opposite the crank. When the eccentric is at full throw, 
the diagram becomes an exact counterpart of Fig. 7 in a re- 
versed position ; but suppose the valve were to cut off steam at 
one-quarter of the piston-stroke, without changing its travel, 
then the chord 1-4 would become short and steep, as shown, 
and the eccentric would be advanced to a position at right angles 
to this chord, and the lap would have to be increased, as repre- 
sented by the increased distance of the chord from the center. 
But as the lap of the valve cannot vary, its travel must be re- 
duced in order to obtain the requisite proportion between lap 
and travel ; and this is effected by moving the eccentric from A 
to point B, where a tangent to the lap circle, at right angles to 
the eccentric-arm, will cut off an arc of the reduced circle of 
rotation through B, which arc, or its center angle, represents 
period of admission within the prescribed limits for one-quarter 
of the piston-stroke. The small shaded segment shows the 
port-opening, which is remarkably small considering that such 
engines often carry full load when the valve is cutting off at 
that point in the stroke. 

It should be noted that the velocity of the piston varies — 
it is greatest at mid-stroke and becomes nil at the ends — and 
that the efficiency of the port-opening depends on the local 
speed of the piston. For this reason only a very small opening 
is required for admission of steam at the beginning of the 
stroke ; but at one-quarter of the stroke the piston-speed has 
greatly increased, and in order to get a good " steam-line " and 
a "square cut-off" there should be ample steam -opening near 
the point of cut-off. Fig. 9 shows clearly how unfavorable the 
conditions are for a square cut-off early in the stroke of single- 
valve "automatic engines" and locomotives, and how incom- 



THE COMMON SLIDE-VALVE. 23 

parably better the conditions become by later cut-off. An early 
cut-off by a single valve must, in any event, reduce the port- 
opening considerably on account of the long l^p required ; but 
by automatic or adjustable cut-off, it becomes still smaller, on 
account of the reduced valve travel. It is also worthy of notice 
that the rapidity of the valve action is less by early cut-off, 
because this occurs when the eccentric is near the extreme of 
its travel, where its lateral motion is comparatively slow. The 
port opening, when steam follows one-quarter of the stroke is, in 
the case here considered, about one-sixth of the maximum open- 
ing, or about three-sixteenths of an inch for a 1 2-inch cyhnder. 

The exhaust eccentric is supposed to be fixed on the shaft, 
giving a constant valve travel and fixed points of release and 
exhaust closure, as in Fig. 7. With direct valve connection and 
exhaust escaping over the inside port edges, the exhaust eccen- 
tric would be in position A ; but in the case under considera- 
tion, the exhaust is supposed to take place over the outside edges 
of the ports, and the eccentric will, therefore, be at point 8, 
diametrically opposite point A. 

If steam and exhaust valves were driven by one eccentric, 
the slanting lines in the diagram would be parallel, and when 
steam is cut off at one-quarter stroke, the exhaust opening and 
closure would be at O and N respectively ; which means prema- 
ture release and much compression. By using two eccentrics 
the early release is avoided, and the compression, being con- 
stant, is better adapted to promote smooth running under all 
conditions. Lap may be used to advantage on a separate ex- 
haust-valve. 

Note that in this diagram the slanting lines are, as a rule, 
not parallel. 

It should also be noted that the opening for exhaust is al- 
ways ample, and takes place when the eccentric is at or near its 
half-throw, and that, therefore, an early release is not required. 

As here represented, the fixed travel of the exhaust -valve is 



24 THE SLIDE-VALVE AND ITS FUNCTIONS. 

equal to the maximum travel of the steam-valve ; but this is 
evidently not necessary, as a much shorter travel of the exhaust- 
valve would give ample opening for release. When a single 
valve controls both steam and exhaust, the exhaust lap is usu- 
ally omitted ; and though the exhaust opening is much reduced 
by the reduced throw, it is still ample when steam is cut off at 
one-quarter of the stroke ; and as the exhaust lead is nearly 
constant, the very early release must be detrimental to steam 
economy. 

The ideal indicator diagram, annexed to Fig. 9, illustrates 
the action of an automatic admission and cut-off yalve in combi- 
nation with a separate exhaust-valve, and dotted lines show the 
corresponding action of a single combination-valve, the point of 
cut-off in both cases being at one-quarter of the piston-stroke. 

If preferred, the diagram Fig. 7 may be used for shiftable 
eccentrics. It will only be necessary to draw the shifting-path 
of the eccentric on the other side of the center, where it is to 
be considered as a construction line only. 

VARIATION IN PORT-OPENING. 

Diagram 10 represents variation in port -opening. When 
steam is cut off at one-quarter of the piston-stroke, the variation 
is represented by consecutive ordinates in the shaded areas, and 
the light areas show the variation when steam is cut off a little 
before three-quarters of the stroke. Admission and exhaust 
are here supposed to be controlled by a single valve, and the 
exhaust-opening is represented by ordinates to the lower curve. 
Ordinates to the crank-circle represent — on the proper scale — 
velocity of the piston, and it will be noticed that at one-quarter 
stroke it has nearly attained its maximum velocity. 

For a given point of cut-off, a certain relation exists between 
lap and travel, and for earlier cut-offs the lap becomes greater, 
or else the travel becorries less. If the lap for a given cut-off 
is increased, the travel must increase at the same rate or nearly 



THE COMMOX SLIDE-VALVE. 



25 



Piston Stroke 



SO ; and the port-opening, bearing a fixed relation to the lap and 
travel, is increased proportionally. Hence, ±>y increasing the 
lap of a valve of variable travel, the por^-opening is also in- 
creased ; but the increased lap curtails th^range of cut-off, for 
the latest cut-off is determined by the relation of lap to maxi- 
mum travel. In this connection it is sometimes stated that the 
port-opening is proportional to 
the lap, which is absolutely true 
only if the lead is zero, or if it is 
directly proportional to the travel. 
A wide range of power is 
often desired in automatic cut-off 
engines, 25 to 35 per cent above 
the rated or economical load is 
specified, and the valve and gov- 
ernor must be designed to meet 
this requirement. An extreme 
cut-off at three-quarters of the 
stroke is sometimes imperative ; Fig. 10. 

but at the same time, it should be kept in mind that there is a 
certain desirable or practical limit to the travel of the valve, and 
that by extending the range of cut-off the port-opening for 
earlier cut-offs becomes smaller. Let the travel be four inches, 
^nd let the latest cut-off be at three-quarters of the stroke, then 
when cutting off at one-quarter stroke, the port-opening is about 
three-sixteenths of an inch ; but if latest cut-off is at five-eighths 
of the stroke, the port-opening for one-quarter stroke becomes 
about one-quarter of an inch ; and making one-half the stroke, 
the limit for cut-off increases the port-opening for one-quarter 
stroke to five-sixteenths of an inch. 




American Jfachinis^ 



NOTES ABOUT LEAD. 



It used to be general practice to give the valve a constant 
lead, irrespective of the point of cut-off ; but the theory in sup- 



2G THE SLIDE-VALVE AND ITS FUNCTIONS. 

port of this practice is now fast becoming obsolete, and later 
experience has established the fact that the lead may vary con- 
siderably without detriment to smooth running. 

Lead means width of port-opening at commencement of the 
stroke ; and no reference is made to the period of lead or lead 
angle, as represented by arc 1-2, or by the intercepted angle, 
though it seems quite proper to take this — the time element — 
in account. Assuming a constant lead, the lead period will vary 
according to the location of the point of cut-off. By earlier cut- 
off the steam is admitted earlier to the cylinder, and it has con- 
sequently more time to fill the clearance spaces ; it will be more 
effective on that account, and it can hardly be disputed that this 
is of as much consequence as the extent of port-opening at the 
end of the return stroke — or perhaps more so. 

If in Fig. 9, the path ABC is made straight and perpendicu- 
lar, the lead will be constant ; and any desired variation in lead 
may evidently be obtained by making the eccentric shiftable in 
other directions, more or less deviating from the perpendicular. 
In the particular case represented in Fig. 9, the lead decreases 
to nothing at the point of minimum throw, and when the eccen- 
tric is near this point, the port-opening becomes exceedingly small; 
but if the valve has some lead at this point, it will become the 
minimum port -opening, and it would make a comparatively large 
addition to the port-opening by very early cut-off, and less " wire- 
drawing " of the steam would probably be the result ; but 
according to later theories, wire-drawing under these conditions 
is beneficial ; for, by lowering the initial steam pressure, and by 
rendering somewhat drier steam, it reduces the initial condensa- 
tion in the cylinder ; and it is claimed that in case of a single- 
valve engine early admission is unnecessary in any event, because 
an early exhaust closure, incidental to early cut-off, fills the 
clearance space with compressed exhaust steam. 

It is also easily proven that by curtailing the lead, the angu- 
lar advance is diminished, and release and exhaust closure occur 
correspondingly later in the stroke. 



THE COMMON SLIDE-VALVE. 27 

Negative lead in conjunction with short cut-off has the un- 
doubted practical advantage that it will always insure perfect 
control of the speed of the engine when rtuining light, whether 
the valve is set exactly central or not ; and it becomes a particu- 
larly useful expedient when the engine (is connected with a con- 
denser. 

If there be any positive lead, the clearance space will fill with 
full-pressure steam before the commencement of the stroke, and 
the expansion of this steam may run the engine if the back pressure 
is light. Much depends on the clearance space. Let it be 8 
per cent of the piston displacement, and let the initial absolute 
pressure be 1 1 5 pounds per square inch ; then the absolute mean 
pressure during expansion of the clearance steam will be 23 
pounds ; but, if the clearance were 4 per cent of the displace- 
ment, the absolute mean pressure would be 15 pounds only. 
The frictional load is a variable or unknown quantity, and it 
may be very small when the engine is directly connected with a 
dynamo. With atmospheric back pressure and heavy compres- 
sion there is little danger of the engine ''running away," but 
when condensing the conditions are quite different. 

COMPRESSION. 

It should be noted that the height of the compression curve 
varies inversely as the clearance, and that, therefore, early ex- 
haust closure is compatible with a large clearance space, w^iile it 
may be objectionable in connection with small clearance. 

In single-valve engines and locomotives the work done in 
the cylinder is partly regulated by the variable compression, and 
the variation of the point of cut-off is therefore less than where 
a fixed eccentric governs the exhaust, and the excessive wire- 
drawing of steam incidental to very early cut-off is thereby partly 
avoided. Otherwise there is nothing gained by variable com- 
pression ; for, according to D. K. Clark, the absolute loss by ini- 
tial condensation is nearly constant for all points of cut-off up to 



28 THE SLIDE-VALVE AND ITS FUNCTIONS. 

35 per cent of the stroke ; and the ratio of useful work to waste, 
or the cyhnder efficiency at early cut-off, depends therefore en- 
tirely on the work done per stroke of engine, irrespective of the 
point of cut-off. 

The height of the compression curve in the indicator diagram 
depends on the point where compression commences, on the 
clearance space, and on the absolute back pressure or density of 
the exhaust — the greater the back pressure, the higher the curve. 
And as it may reasonably be assumed that the most economical 
compression is that which fills the clearance space with steam of 
nearly same density as the entering steam, the pressure of this 
should also be taken into account. 

From this point of view it appears that under certain condi- 
tions the single combination valve may become the ideal valve, 
and that such conditions may exist in the high-pressure cylinder 
of certain compound engines, where the receiver or back press- 
ure varies according to the point of cut-off, being greatest with 
late cut-off and late exhaust closure, and diminishing as the 
point of cut-off and exhaust closure advances ; for this may, 
under the conditions imposed by a single combination valve, 
lead to a nearly fixed condition of density of the compressed 
steam. 

Judging from the above remarks, it will readily b^ agreed that 
a fixed rule for the determination of travel, lap, lead and port- 
opening may become worse than useless on account of our de- 
ficient knowledge of what is required for best economy, and that 
a wide scope may be given to practical considerations. 

THE MOTION OF LOCOMOTIVE VALVES. 

To construct a locomotive valve diagram, it is only necessary 
to substitute for the link-gear an equivalent single shif table ec- 
centric ; that is, to find the path of the center of a shiftable 
eccentric which will produce the same valve-motion as does the 
link. 



THE COMMON SL/DE-VALJ'E. 



29 



Fig. 1 1 represents diagramatically the chief mechanism of 
a stationary link at mid-gear, and the positions of crank and 
eccentric centers are indicated. The virfual angle of advance, 
which should be used in the valve dia^am, is a little greater 
than the actual angle ; and the diagram (shows how to obtain it. 




The lead is constant, and the straight line ACA represeuriv the 
path of the equivalent shifting-eccentric ; but the distance AC 
is sufficient for the valve diagram. 

Diagrams 12 and 13 represent ''shifting-links" with "open" 
and "crossed" rods respectively. The valve is supposed to 



80 THE SLIDE-VALVE AND ITS FUNCTIONS. 

be moved by a counter-arm rocker, which is not shown ; and 
this requires the eccentrics to be placed on the crank-side 
of the shaft, or diam.etrically opposite the position they would 
take if there were no intermedial reversal of the link motion. 
In full gear the motion is supposed to be governed entirely by 
one of the eccentrics, that is, when the throw of the link-block 
equals the throw of the eccentric ; but in mid-gear the motion is 
governed by the two eccentrics jointly, and if the angularity of 
the rods were the same for both dead-center positions of the 
crank, the mid-gear throw would be exactly as that of a single 
eccentric located at the center of a straight line joining the two 
eccentric centers, and the lead of the valve would be constant 
for the entire range of cut-off. But, owing to the fact that the 
angularity of the rods is not the same on both centers, the mid- 
gear valve motion will be increased with open rods and dimin- 
ished with crossed rods, and the mid-gear lead will be increased 
or diminished proportionally. The shifting-path of the single 
equivalent eccentric will, therefore, be curved as shown in the 
figures. 

If it is desired to equalize the lead for both ends of the 
cylinder, the link must conform to a certain curve ; and any 
variation from this curve will make the lead unequal for back 
and forward centers for all points of cut-off but one, and this 
point may be fixed at will by lengthening or shortening the 
valve-stem connection. 

How to lay down the shifting-path of the equivalent single 
eccentric is shown in the diagram, and it is also shown how to 
locate the central point in the link arc, so as to give uniformly 
equal lead at both cylinders ends. The letter A denotes a cer- 
tain distance or unit measurement, and its designation in the 
figures makes any textual explanation unnecessary. The eccen- 
tric-rod is supposed to be directly in line with the rocker-pin in 
two full-gear positions. 

The rocking motion of the link may cause a marked dis- 



THE COMMON SLIDE-VALVE. 31 

placement of the point of cut-off, if the link and saddle pins are 
not properly located ; but as this involves the valve-gear only, 
it will not be discussed here. r 

The shifting-link with open rods/ is most commonly used on 
American locomotives ; and it is noteworthy that this gear pro- 
vides maximum lead in combination with early cut-off, which is 
the reverse of stationary engine practice. The heavy compres- 
sion in mid-gear may reverse the strains gradually, while, with 
light compression in full gear, and at slower speed, excessive 
lead may cause a violent reversal of the strains. 

Variable lead is unavoidable with the shifting-link, but the 
lead may be reduced to any extent and made partly negative by 
providing sufficient lap or by moving the eccentrics back. 

MULTIPORTING. 

After Corliss had established the superior economy of early 
cut-off, and by his peculiar valve-gear had produced a nearly 
sharp cut-off at moderate speed, it became almost an axiom that 
a sharp cut-off is essential for best economy ; and it has appar- 
rently been the object of engine-builders, ever since, to produce 
an indicator-diagram with *' square cut-off" — which means a 
nearly horizontal "steam-line" terminating abruptly where it 
joins the expansion line. 

The slanting steam-line and round corner is the result of 
"wire-drawing," which is another name for free expansion; but 
it is also due to the working expansion of the steam already in 
the cylinder. While the free expansion, in one sense, represents 
a direct loss, it may, at the same time, have a beneficial effect, 
if the steam is not absolutely dry; and it is, therefore, just 
possible that the slanting steam-line and the round corner does 
not represent any actual loss. 

No actual knowledge, however, can result from mere reasoning 
in this case ; but the question might be settled by careful test- 
ing, which to the writer's knowledge has never been attempted. 



S2 THE SLIDE-VALVE AND ITS FUNCTIONS. 

In order to obtain sufficient port-opening with reduced 
travel, many valves have one or two supplementary steam-pas- 
sages, which communicate with each steam-port and into which 
steam is admitted over special steam edges, which open and close 
for steam admission simultaneous with the main steam edges. 

How much this actually improves the steam-line on the 
indicator card has probably never been fully investigated, or 
experimental results have not been published. Such experi- 
menting would be extremely simple ; for the supplementary ports 
in the valve could easily be temporarily blocked, and it may 
have been tried in some university laboratory. 

Common sense suggests that two port-openings will give a 
better steam-line and sharper cut-off than one opening, but 
nothing definite is known about it. Many incidents in steam- 
engine practice may be accounted for by the hypothesis that a 
sharp local obstruction in the steam-passage has an almost im- 
perceptible effect, until the free opening has been reduced to a 
certain extent, after which a rapid decrease in the flow follows ; 
and if that be so, the next pertinent question is : How much 
may the opening be reduced before this critical point is reached ? 

In this connection, the fact should be recognized that the 
indicator diagram is not a reliable criterion on steam economy ; 
also that a valve which will stay comparatively tight is a require- 
ment of prime importance, for whatever the loss or gain by 
wire-drawing, compression, release, etc., the peculiar steam dis- 
tribution due to leakinor of the valve can under no circumstances 
be profitable ; and as a multiplication of the port-openings may 
increase the inevitable leakage loss, it is quite evident that if no 
objection could be raised to the round corner and slanting steam- 
line on the indicator card, many valves would be reconstructed. 

SETTING THE ENGINE ON DEAD CENTERS. 

When the piston is at the end of its stroke, and the connect- 
ing-rod is right on the center line of the engine, in line with 



THE COMMON SLIDE-VALVE. oo 

the crank-shaft, then no amount of steam pressure will put the 
crank in motion, and the engine is therefore said to be on its 
dead center. When near the dead point the piston-motion 
becomes very slow, and it is actually reduced to nothing at the 
moment when the motion is revbi^sed. Near the end of the 
stroke the crank-motion is nearly at right angle to the piston- 
motion, and it becomes actually so at the moment the crank 
passes the center line. At, or near, this point there is very 
little motion of the cross-head — it becomes nearly stationary — 
and it is, therefore, very difficult to determine the dead center 
position of the crank by observing the motion of the cross-head. 
On the other hand, the eccentric is not far from mid-throw ; 
and the slide-valve is, therefore, moving rapidly at that point ; 
and in order to set it to its proper lead at the commencement 
of the stroke, the exact dead-center position of the crank must 
be ascertained. It may be done in the following manner : 

Place crank near dead-center, and make a mark at the edge 
of the wheel by placing a tram, or stick, against the floor, or 
some other fixed object near the rim of the wheel ; also mark 
position of cross-head ; then turn engine over dead center until 
cross-head returns to position first marked ; mark rim again with 
same tram, in same manner. Now put a mark on rim centrally 
between the two tram-marks, and turn wheel till this mark coin- 
cides with tram-point. This is the exact dead-center position. 
Locate the opposite dead center in exactly the same manner, 
and set the valve to give equal leads. If there is lost motion in 
the brasses it is not possible to determine the stroke of the 
piston exactly, but any material error in the valve-setting may 
be obviated by turning the crank in one direction only. 



3^ 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



CHAPTER II. 

IMPROVED SLIDE-VALVES. 

THE DOUBLE-PORTED MARINE SLIDE-VALVE. 

Plain double-ported slide-valves, constructed as shown in 
Fig. 14, are often used on marine engines. The valve is shown 
in its middle position, and it will be observed that the two con- 
jugate ports are exactly alike, and that they are opened and 
closed simultaneously. Transverse tapered passages in the 
valve admit steam from the steam-chest to the inner ports, and 




Fig. 14. Double-Ported Marine Slide-Valve. 



a central duct, cored in the valve, conveys the exhaust from 
the outer ports, over the transverse steam-passages to the com- 
mon central exhaust opening. 

In marine engines the intermediate and low-pressure valves 
are not used for short cut-off ; but as the throw is usually the 
same for all the cylinders, and therefore proportionately short 
for the large cylinders, double ports become desirable. In such 
cylinders the unbalanced pressure is moderate, and unbalanced 
valves with short throw work satisfactory. 



IMPRO VED SLIDE- VA L VES. 



35 



For the smaller cylinders — where smaller valves are re- 
quired, and the throw is comparatively greater, and where the 
differential pressure occasionally^ecomes considerable, and 
where the high temperature n^es lubrication less effective — • 
single-ported piston-valves are generally used. 

The double ports necessarily increase the clearance and the 
cooling surface ; but in large cylinders, where steam is cut off 
near half stroke and extreme variation in temperature is 
avoided, this becomes of less consequence. 

Quite a number of special valve-gears are in use, by which a 
quick and ample port opening is obtained with early cut-off, and 
thus one of the objections to single-valve variable cut-off is 
removed ; but, as previously explained, the evil of premature 
release and variable compression are attributes of the single 
valve, and cannot be amended or ameliorated by any simple 
valve g-ear. 



THE ALLEN LOCOMOTIVE VALVE.* 

As representatives of the double admission type, the Allen 
locomotive-valve and the Straight-Line balanced valve are 
shown in Figs. 15 and 16. 




Fig. 15. The Allen Locomotive Valve. 

In the Allen valve. Fig. 15, a single, long, double-ported 
steam-passage, A, takes steam over supplementary steam edges, 
so located as to open and close the entrance opening of the pas- 

* This valve is called the Trick valve in Germany, after the German inventor. 



36 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



sage simultaneously with the opening and closing of the main 
port. This passage never communicates with the exhaust ; for 
its outlet to the main port is closed just before the port opens 
for release, and it is opened just after the port is closed for the 
exhaust, and it is then filled with compressed exhaust steam. 
By short travel the heavy compression fills it with dense steam, 
and it ought to serve its purpose well ; but when the travel of 
the valve is increased under heavy load, it becomes of no use, 
and there will then be a small loss by filling it with live steam 
at the commencement of each stroke. 

THE STRAIGHT-LINE BALANCED VALVE. 

The Straight-Line valve, Fig. i6, is the pioneer, and em- 
bodies all the principal features of the class of valves it repre- 
sents. It is a double-faced valve, the two opposite faces being 
exactly alike. It is confined between the cylinder valve-face 
and an exactly similar face of the stationary ''pressure-plate" C, 
which plate carries the unbalanced steam pressure that would 




Fig. 1 6. The Straight-Line Valve. 

otherwise be carried by the valve. This pressure plate is held 
in its proper position by distance pieces, which allow the valve 
to move freely between the opposite faces. This construction 
provides two pairs of steam edges at each end of the valve, and 
two port openings are obtained, as shown by the arrows. The 
passage A conveys the steam from the shallow recess in the 
pressure plate to the main port, and it operates exactly as 



' IMPROVED SLIDE-VALVES. 37 

the corresponding passage in the Allen valve. It is therefore 
desirable to restrict this space as much as is possible without 
destroying its usefulness. IrT case of the flat balanced valve, 
this presents no practic^fldifficulty ; but such narrow passage 
could not easily be cast ih^an Allen valve. 

The recesses in the pressure plate are not merely steam- 
passages, they are also there to equalize the pressure on both 
sides of the valve. They may be considered as extensions of 
the main steam-passages and as additions to the clearance 
space ; and being half the time exposed to exhaust steam, the 
additional surface they expose to the entering steam is one of 
the less desirable features of this and all other balanced 
valves. 

The main object with the exhaust passage B is to get a 
'' quick " opening and closing of the exhaust, so as to avoid 
*' wire-drawing." After the exhaust is cut off part of it is com- 
pressed in this space, and is bottled up there before live steam 
enters the port ; and directly after this is cut off the bottled-up 
steam is allowed to mingle with the expanding steam in the 
cylinder. 

If a considerable quantity of water is carried over in the 
cyhnder it may fill the clearance space, and force the valve and 
pressure-plate from their seats, while the water is discharged in 
the steam-chest ; and thus the cylinder is relieved of a danger- 
ous strain, while the clatter of the valve attracts the attention 
of the engineer. 

This valve is used in connection with a shaft governor, which 
automatically changes the throw and angular advance of the 
eccentric by shifting it across the shaft. 

An automatic induction valve of the Straight^Line type is 
sometimes used conjointly with an exhaust valve of the same 
type actuated by a permanent eccentric. These valves are 
placed on opposite sides of the cylinder, and are similar in con- 
struction to the combination valve shown in Fig. i6. The 



38 THE SLIDE-VALVE AND IIS FUNCTIONS. 

main object with this arrangement is to have constant release 
and compression, as explained in the first chapter. 

The exhaust pressure-plate must be held to its seat by 
mechanical means ; and it may be done by springs, in which case 
it affords a direct escape for entrapped water to the exhaust 
pipe. 

It is questionable whether a double exhaust opening is use- 
ful, or even desirable, if the valve has no exhaust lap ; for in 
that case, it opens and closes for the exhaust when the eccentric 
is at "half throw," which is the most favorable condition for 
rapid action ; and as the exhaust opening for such valve is equal 
to lap plus lead, irrespective of the throw, when the opposite 
steam-port opens, or practically at the end of the stroke, the 
early release cannot be necessary ; and it is a natural conclusion 
that a slow opening will be advantageous under such conditions. 
The exhaust closure cannot be too "quick," but it is a question 
if the loss by quick opening is not greater than the gain by 
quick closing. With late admission and some exhaust lap, two 
exhaust openings may become desirable. 

VARIATIONS OF THE STRAIGHT-LINE VALVE. 

The valves and pressure-plates of the Straight-Line type are 
sometimes so constructed that they cannot be forced from their 
seats, and these valves admit steam through a central opening, 
and exhaust it over the outside edges ; which leaves exhaust 
pressure in the steam-chest and makes packing of chest cover 
and stem easy, and it also allows examination of the valve with 
steam-pressure on. The transposition of steam- and exhaust- 
edges brings the eccentric in a diametrically opposite position 
on the shaft. 

Some valves of the Straight-Line type open and close for 
steam simultaneously in four places, in which case two extra 
pairs of steam edges on opposite valve-faces are disposed much 
like the two supplementary steam edges of the Allen valve, and 



IMPROVED SLIDE- VAL VES. 



39 



this necessitates one or two steam-passages lengthwise through 
the valve body. By reason of the double face twice as many 
openings are obtained as with: the single-faced Allen valve. 



THE McEWEN VALVE. 



A slide-valve is supposed to be in perfect equilibrium when 
the steam-pressure is equally distributed on opposite faces, 
neglecting the weight of the valve, which is generally of Httle 
consequence. This condition is presumed to be satisfactorily 




Fig. 17. The McEwen Valve. 

fulfilled when there are channels or recesses, back of the valve, 
in form and area equal to, and exactly opposite the ports and 
the exhaust area in front of the valve, and means provided for 
continuous communication between opposite sides. It must, 
however, be admitted that, under the conditions which generally 



40 



THE SLIDE-VALVE AND ITS TUNC 1 IONS. 



O 



o 



o 



o 



prevail, the intensity of the pressure on both sides of a balanced 
valve cannot be absolutely uniform ; for when the ports are 
only partly covered by the valve, and steam is rushing through 
the ports with a velocity of one hundred feet, or more, per 
second, there is practically no pressure on that surface which 
overlaps the port edge, while the pressure on the corresponding 
opposite surface, on the back of the valve, must of necessity be 
considerably greater, partly on account of the dynamic effect 
of the steam, and partly from the resistance the flow of steam 
encounters in the passages back of the valve. 

This undesirable . feature is avoided in the design of the 
McEwen valve, shown in section in Fig. 17. The valve is 

of flat, rectangular 
form, and is of the 
"Straight-Line" type; 
but, unlike Professor 
Sweet's valve, it has 
no auxiliary passage 
through the valve. 
The valve is covered 
by a pressure-plate, in 
which are auxiliary 
steam-passages, the 
ports of which are 
opposite to the ports in front of the valve, and being simul- 
taneously uncovered by the valve, these ports permit the steam 
to flow in opposite directions from opposite valve-fades, thus 
leaving the valve in perfect equilibrium. 

The valve-face on the cylinder is shown in Fig. 18, and it 
will be understood that the pressure plate has four hollow legs, 
by which steam is conducted through the four smaller ports 
into the main steam-passages to the cylinder ; and the exhaust 
will escape through the same ports. 



O 



o 



1 




"11 


. 1 
1 



O r 



O 



O 



o 



o 



o 



o 



o 



o 



o 



Fig. 18. 



IMPR O VED SLIDE- VA L VES. 



41 



THE BALL TELESCOPIC VALVE. 



The excessive unbalanced pressure on the common D-valve, 
which causes friction artel rapid wear, is mainly due to the large 
exhaust cavity which permanently removes steam-pressure from 
a large area on the face-side of the valve, while the entire rear 
side is exposed to full steam-pressure. By admitting steam 
through a central opening in the valve, and exhausting it over 
the outside edges, the exhaust cavity is dispensed with, and the 
unbalanced pressure is thereby greatly reduced. 

A valve designed on this principle by Mr. Frank H. Ball is 
represented in Fig. 19, which shows the valve in its central 




Fig. 19. The Ball Telescopic Valve. 

position in the steam-chest. It is a double-faced valve, and it 
consists of two telescopically connected parts. Each part con- 
sists of a flat rectangular frame, which covers the ports in its 
central position, and on which is a short hollow cylinder. One 
of these cylinders fits inside the other, and it has three grooves 
containing packing-rings. As these rings do not wear at all 
they remain steam tight when properly fitted. Steam is 
admitted to the inside of the valve, as shown, and the exhaust 



42 THE SLIDE-VALVE AND ITS FUNCTIONS. 

escapes over the outside edges into the steam-chest. The only- 
unbalanced area is that portion of the steam-ports which is 
opposite the cylindrical part of the valve during the exhaust 
period ; and taking the counter pressure into account, the valve 
is so proportioned as to leave sufficient unbalanced pressure to 
insure a close contact between the working faces. This valve 
has the undoubted advantage that it will follow up its own 
wear ; and the claim made for it, that it remains steam tight 
throughout its entire life, does not seem unreasonable ; and, 
moreover, this claim is backed by seventeen years' experience. 

The double-port opening is particularly useful when the 
steam is cut off early by reduced valve travel ; but it will be 
noticed that the valve-faces are horizontal, or parallel with 
the top and bottom of the steam-chest, which necessitates a 
divided and somewhat distorted steam-passage to the cylinder, 
and is a feature which some designers studiously avoid. 

BALANCING A COMMON D-VALVE. 

The extreme changes of temperature in cylinder castings 
may warp the valve-faces ; and for this and other reasons a plain 
slide-valve, provided with a self-adjusting pressure-relieving de- 
vice on its back, is often used. As the surfaces are self-adjust- 
ing extraordinary nice fitting is not essential, and if there is a 
leakage it is apt to diminish by wear ; and if much water gets 
into the cylinder it may escape to the steam-chest by pushing 
the valve back from its seat. Such a valve cannot be perfectly 
balanced ; for the counter-pressure on the face depends to some 
extent on the position of the valve, and is, therefore, not quite 
uniform. 

Fig. 20 shows a plain slide-valve with a pressure-relieving 
device suitable for a horizontal low-pressure cylinder. It con- 
sists of a ring, cast on the back of the valve, and a loose flanged 
ring, fitted inside it. The ring bears against the steam-chest 
cover and keeps steam away from the back of the valve. 



IMPRO VED SLIDE- VAL VES. 



43 



The space inside the ring must communicate with the exhaust^ 
and in the case here illustrated the circular opening extends 
through the back of l^he valve to the exhaust cavity. Small 
helical springs are /jSlaced so as to keep the ring out when the 
engine is started. ^ 

The valve here shown was designed for the low-pressure 
cylinder of a non-condensing engine and for a fixed cut-off 
at three-eighths of the stroke. To prevent the compression 
from forcing the valve out against low receiver-pressure the 
ports were reduced to about half their usual size, as shown ; 
and, as mentioned in chapter i, this had no appreciable effect 
on the exhaust. The relieved area 
is that inclosed by the outside cir- 
cumference of the inside ring or the 
inside circumference of the outside 
ring, and for a non-condensing engine 
it should not exceed three-quarters of 
the area between exhaust edges. For 
condensing engines it could and ought 
to be nearly equal to this whole area ; 
but as all engines may incidentally run 
non-condensing, it is probably advis- 
able to provide for such occurrence. 

On high-pressure cylinders the ring 
area is often made equal to the area 
between exhaust-edges plus the area of 
one port. 

The pressure that keeps the ring against the steam chest 
cover is determined by the difference in pressure on both sides 
of the flange A. Professor S. W. Robinson has shown experi- 
mentally that a sliding surface which separates exhaust from 
'* live steam " is exposed to pressure of '' creeping " steam, which 
decreases nearly uniformly from the steam side to the exhaust 
side ; and it may reasonably be assumed that, when one surface 





Fig. 20. Plain Valve, 
Partly Balanced. 



44 THE SLIDE-VALVE AND ITS FUA'CTIONS. 

is sliding over another surface which is alternately exposed to 
steam- and exhaust-pressure or high- and low-pressure steam, the 
mean pressure between the surfaces will be a mean between 
the extremes on either side ; but it may also reasonably be ^- 
pected that, by the reciprocating motion, the interv^ening pres- 
sure becomes somewhat uneven at the two extremities of the 
travel ; for at one end the covered surface is never fully exposed 
to the lower pressure, and at the other end it is never exposed 
to the higher pressure, and in the extreme positions the interven- 
ing pressure may, therefore, alternately apj^roach the higher and 
lower pressure at diametrically opposite points of the ring. 
On one face of ,the flange is full receiver-pressure, and on 
the other face is the variable intervening pressure ; and it will 
readily be understood why it has been found necessary, in order 
to insure permanent contact, to make both flange areas equal 
by turning down a shallow recess, as shown. The flange A can 
be from three-quarters to one inch wide, and the springs should 
be very light. Similar devices are often used on locomotives. 

THE RICHARDSON BALANCED VALVE. 

The Richardson balancing device, much used on locomotives, 
consists of straight metal strips, which fit steam-tight in grooves 
on the back of the valve, and are held against the steam-chest 
cover by steam-pressure and springs. These strips inclose a 
rectangular area which communicates with the exhaust cavity 
through a small opening in the back of the valve. 

THE THOMAS BALANCE. 

Fig. 21 represents a balancing device invented by Mr. W. J. 
Thomas and much used on locomotives. The ring A is open in 
one place and is expanded some by being forced on its conical 
seat ; it is therefore self-adjusting, both against the conical sur- 
face and against the planed surface of the steam-chest cover, 
and the steam-pressure on the circumference of the ring insures 



IMPR O I 'ED SLIDE- VA L VES, 



43 



a tight joint between the ring and the cone. By using the 
proper taper, the resultant pressure against the steam-chest cover 
IS made sufficient to overbalance the counter-pressure of creep- 

ino- steam between /the rins; and the cover. The differential 

■& ( 

pressure on the valve-face is determined by the relative propor- 
tion of the relieved area. In locomotives due allowance must 
be made for rem. oval of the valve-yoke, and, therefore, a remov- 
able disk is used, as shown in the cut. If the steam-chest is 
narrow, two rings may be placed side by side on cones cast on 
the valve. 

The manufacturers have established the following rule : Bal- 
ance-ring areas are made equal to ''area of one steam-port, two 




Fig. 21. The Thomas Balance. 



bridges and the exhaust-port plus 8 per cent if for single bal- 
ance, and plus 15 per cent if for double balance." It may ap- 
pear as if more pressure is removed from the back of the valve 
than would ordinarily be considered safe, but the apparent 
anomaly disappears when it is considered that the reaction from 
the bevel ring-surface must be balanced ; and the friction of the 
conical joint, no doubt, serves a good purpose by opposing the 
counter-pressure of the exhaust-steam when the link is at mid- 
gear. The opening, cut in the ring in order to expand it, is cov- 
ered by an L-shaped joint-plate, which fits against the cone and 
is flush with the top of the ring, and forms a steam-tight joint in 
both places. The rings are made of hard, close-grained cast iron ; 



46 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



and the outer rim, shown in the sketch, is there to prevent acci- 
dent if the ring should break. As the ring is held firmly against 
the cone, there is no wear on this ; and the ring, being self-adjust- 
ing, is admirably adapted for the interchangeable system preva- 
lent in locomotive works. This device may readily be fitted to 
any common slide-valve or double-admission valve. 

That more balance area is required with double rings is evi- 
dently due to the fact that the circumference of two rings com- 
bined is more than that of one ring inclosing the same area, and 
the push against the valve-seat, from the conical ring surfaces 
becomes correspondingly greater. 



PISTON-VALVES. 



Piston-valves are cylindrical valves moving in the direction of 
their axis. Usually steam is admitted centrally, and the steam- 
ports open into annular spaces surrounding the valve, by which 
a perfect balance is obtained. They are simply balanced sUde- 




Fig. 22. Double-Admission Piston-Valve. 

valves of convenient form, and are designed for single or double 
admission on the same principle as the flat valve. Fig. 22 shows 
a double-admission piston-valve in its central position, with steam- 
laps on the inside between the ports. The passage A, in con- 
junction with the narrow annular ports, provides for double ad- 



JMPR VED SLIDE- VAL VES. 



4T 



mission, as does the corresponding passage of the Allen valve ; 
and like this it should be so placed that it never communicates 
with the exhaust, in orderto save the residual steam it contains 
and to avoid condensation. The admission-edge and the exhaust- 
edge of a piston-valvfr^ extend all around its circumference, and 
for this reason a comparatively small diameter will give sufficient 
port-opening. Double-admission piston-valves are seldom pro- 
vided with adjustable packing-rings, while it is common on single- 
admission valves. All piston-valves work in removable bush- 
ings, in which the ports are cut out. Judging from recent prac- 
tice the double-admission piston-valve may become obsolete. 

VALVES OF THE "IDEAL ENGINE." 

Piston-valves of the "Ideal Engine" are shown in Figs. 23 
and 24. One is a plain valve without rings, and the other is an 
" expansive " valve. Only one end of the latter is shown, and the 
scale is sufficiently large to show details of construction plainly. 

The two rings, A, are made to fit the bore accurately, and 




T 



?^ 



Fig. 23. " Ideal " Valve. 

are then split to allow of some expansion. They are not " spring- 
rings," for they are thick and not made larger than the valve-bore 
of the cylinder. When the valve becomes leaky from wear the 
rings may be expanded a little by turning the head B. This head 



48 



THE SLIDE-VALVE AND ITS FUACTIOXS. 



has a ring-formed extension, on which are four cams or eccentric 
planes. These are accurately machined, and bear on four shoes 
C, which fit against the inside periphery of the expansion rings. 
Thus by turning the head the four shoes are simultaneously 
forced against the rings, and by thus expanding them, a delicate 
adjustment to the proper diameter is made. After adjustment 
is made, the nut D is screwed up tight, clamping the head and 




Fig. 24. The "Ideal" Expansive-Valve. 

rings securely. The object is evidently to avoid the use of spring 
rings, which would wear the valve-seat, and would have to be 
very thin on small valves, and would be liable to break. 

The builders of the Ideal Engine also use flat-balanced valves 
of the Straight-Line type ; and in view of the fact that there has 
at times been a lively controversy about the relative merits of 
these two valve types, the following letter from the Ideal En- 
gine builders is interesting : 

Dear Sir, — In reply to your letter of the 2d inst. Although we offer 
purchasers the option of taking the plain solid valve or our patented adjustable 
valve, three-fourths of our sales are for the plain solid valve. The valve-seats or 



IMPROVED SLIDE-VALVES. 49 

bushings, after being pressed into the steam-chest 'chambers, are bored out with 
a portable bar, and then a reamer put through, and a valve is fitted v^^hich has 
been previously ground on a Brov^-n & Sharpe grinding machine for an accurate 
and close fit. By this method ye get a valve that is perfectly balanced, and is 
practically steam tight, and ret^ires less lubrication than valves of the flat type, 
and, consequently, gives excellent service. Three to five years' service can be bad 
before the valve is worn sufficient to cause excessive loss of steam and require 
renewal ; and then renewal is so easily and cheaply made by means again of the 
portable boring rig. The valves are light and give satisfaction in everybody's 
hands. The adjustable valve is all right, but in hands of careless or incompetent 
engineers it can be expanded so tight as to cause stripping of the valve gear. 

We are also builders of flat balanced valves, but our greatest sales are the 
piston valve; and after having had experience with both types we believe the 
piston valve to be the best commercial design. 
Jan. 6, 1902. 

THE WESTINGHOUSE STANDARD VALVE. 

Fig. 25 (on the following page) represents a sectional view of 
cylinders and valve of a Westinghouse Standard Engine. This 
is a two-cylinder vertical engine, and the cylinders take steam 
on the down-stroke only. Admission and exhaust are controlled 
by a single piston-valve, located between the cylinders. The 
pistons move in opposite directions ; and the cut shows the 
left-hand piston (in sections) at its highest position, and the valve 
just commencing to uncover the steam-port ; while the port 
on the other side is already uncovered sufficiently for a free 
exhaust. The live steam is confined in the annular space, sur- 
rounding the valve, and the hollow valve body . and the upper 
and lower parts of the valve-chamber receive the exhaust steam. 
It will be seen that the valve arrangement is practically the 
same as that of a single-cylinder double-acting engine ; the only 
difference is, that in the case under review, the steam-ports are 
on opposite sides of the valve. 

The small piston above the valve is there to balance the 
reciprocating force of the valve and its connections, that is, to 
overcome the momentum of these parts. The exhaust steam 
and air confined in the upper part of the steam-chest above the 



50 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



piston, is alternately compressed and expanded, and offers an 
elastic resistance, similar to that of a spring, alternately com- 
pressed and extended ; and this elastic force is directly opposed 
to and partly neutralizes the reciprocating force of the valve. 




Fig. 25. The Westinghouse Standard. 

The valve is driven by means of a sh if table eccentric con- 
trolled by a shaft governor, and the point of cut-off is automati- 
cally varied by changing the throw and angular advance of the 
eccentric ; that is, by moving it across the shaft in a suitable 
manner. 

VALVES ON COMPOUND ENGINES. 

The valves of tandem-compound engines are frequently 
driven by a single shifting eccentric, which automatically changes 
the cut-off in both cylinders. In such case the high- and low- 
pressure cut-off must nearly coincide ; for, the angular advance 



IMPRO I 'ED SLIDE- VAL VES. 



51 



being the same for both valves, the cut-off can only be made 
different by varying the laps ; and as this changes the lead it is 
only permissible within narrow limits. Such arrangement is 
probably favorable to clo^e regulation, and it has the advantage 
of great simplicity ; buOvhether it has any economical advan- 
tage or disadvantage has not been practically demonstrated. If 
both valves have the same travel, the port-opening to the low- 
pressure cylinder will be very small comparatively, even if the 
length of the port is proportioned to the cylinder-bore ; and 
on account of the high receiver pressure by early cut-off, a 
"nice" high-pressure "card" cannot be expected when the 
engine is under-loaded. 

Some compound engines have a single piston-valve, driven 
by a shifting eccentric or a link-gear. The cylinders are 
arranged side by side, with the valve in an intermediate or 
parallel position, and both cylin- 
ders and valve-chamber are made 
in one casting ; and in this com- 
bination the piston-valve has prob- 
ably reached the acme of fitness 
and simplicity. Fig. 26 may rep- 
resent a valve of this type for a 
small vertical compound-engine 
having two cranks oppositely dis- 
posed. The central part of the 
valve bushing is surrounded by 
steam, which is admitted through 
an annular port to the annular 
valve-space, which connects with 
the high -pressure cylinder, as shown. The valve has just 
opened for steam to the upper end of the high-pressure cylin- 
der, and the exhaust from the lower end is just entering the 
low-pressure cylinder, while the low-pressure exhaust is escap- 
ing from the upper end through the hollow valve to the lower 




Fig. 26. 



EXH^UST 

Compound Piston- Valve. 



52 THE SLIDE-VALVE ANJJ ITS FUNCTIOXS. 

exhaust-chamber. The steam-distribution is regulated by three 
ports : The central port admits and cuts off steam to the high- 
pressure cylinder, while the two other ports control the admis- 
sion of high-pressure exhaust to the low-pressure cylinder, and 
also the exhaust from this cylinder. The exit from the high- 
pressure cylinder is not directly controlled by the valve ; the 
expanded steam simply gets out as soon as it has a chance to 
go into the low-pressure cylinder. 

Release and exhaust closure in the high-pressure cylinder 
become coincident with admission and cut-off in the low-pressure 
cylinder. The admission lap for the low-pressure side becomes 
the exhaust lap for the high -pressure side. This feature is open 
to criticism ; for some lap is required to avoid excessive lead to 
the low-pressure cylinder, while for the high-pressure exhaust 
no lap or negative lap is preferable, for the compression of the 
intermediate exhaust may otherwise become excessive. Experi- 
ence has established the fact that smooth running is hardly 
obtainable with excessive compression, but as to steam economy 
the only satisfactory answer can be furnished by a strictly sci- 
entific comparative test. 

Considering that space which is always in direct communi- 
cation with the cylinder is "clearance-space," it appears that 
there is no "receiver-space," for the low-pressure cylinder takes 
steam directly from the high-pressure clearance-space. This 
space is extraordinarily large, and when steam and exhaust are 
cut off late in the stroke it may cost something to fill it with 
steam at the commencement of each stroke ; though under cer- 
tain conditions this loss may be very insignificant, considering 
that this space never communicates with the atmosphere or the 
condenser ; and it is probably very useful as a means of keeping 
down the compression in the high-pressure cylinder. These 
valves are usually fitted with packing-rings. 



IMFR O VED SLIDE- VA L VES. 



53 



THE WESTINGHOUSE COMPOUND VALVE. 

Fig. 27 shows the valve of a Westinghouse Compound 
Engme which is vert^ and single-acting. The valve is of 
the piston type, hollow and light, and made steam-tight by 
means of four spring rings. It is operated by means of a 
bell-crank rocker from a shiftable eccentric, controlled by a 
shaft governor. The 
steam-passages are 
formed by a hard cast- 
iron bushing, forced 
into place. By this con- 
struction the ports can 
be machined to exact 
size and register. S 
and E are the steam 
and exhaust chambers 
around the bushing, 
into which connects re- 
spectively the steam 




Fig. 27. The Westinghouse Compound. 



and exhaust pipe. The valve is shown in its central position 
covering the high- and low-pressure ports. The ports consist 
of annular series of openings surrounding the valve. The high- 
pressure port is seen to the left, centrally over the high- pressure 
cylinder. Next to this is an open passage from the high- 
pressure cylinder to the space surrounding the neck of the 
valve. B is a by-pass valve, used only for starting the engine. 
Next to this is the low-pressure port, also covered by the valve* 
The high-pressure port is only for admission to the high- 
pressure cylinder, while the low-pressure port is for admission 
and exhaust to and from the low-pressure cylinder, and it also 
controls the exhaust from the high-pressure cylinder. The 
space around the neck of the valve is part of the clearance 
space of the high-pressure cylinder ; the pressure in this space 



54 THE SLIDE-VALVE AND ITS FUNCTIONS. 

is always the same as that in the adjoining cyHnder, being- 
always in direct communication with it. It is never in direct 
commmiication with the low-pressure exhaust. 

The large high-pressure clearance has been criticised from a 
theoretical standpoint, without regard to the fact that it cannot 
consistently be considered equivalent to, or compared with, the 
clearance of the low-pressure cylinder or that of a simple en- 
gine. This is what the Westinghouse people have to say to 
their critics : '' We have no quarrel with theory, but only with 
mistaken interpretation of theory, and we simply submit that 
the practical results obtained from this design should set at 
naught the unsupported opinion of those who decry the method 
employed." 

The pistons are of the trunk pattern, and it will be observed 
that the low-pressure piston has two diameters. The lower part 
works through an internal sleeve, or cylinder, which connects 
with the crank-case. By this construction the piston displace- 
ments in relation to the crank-case become equal, and suction 
and expulsion of air and oil through the vent-pipe in the crank- 
case is avoided. The air confined in the annular space under- 
neath the large diameter, being alternately compressed and 
expanded, helps to overcome the inertia of the large piston. 

THE VAUCLAIN VALVE. 

The Vauclain Compound Locomotive has one high-pressure 
cylinder and one low-pressure cylinder on each side, and their 
volumetric ratio is about as one to three. They are cast in one 
piece with the valve chamber and saddle, the cylinders being in 
the same vertical plane, and close together. Fig. 28 shows 
the arrangement for "eight-wheel" passenger locomotives. 
The valve is located in the saddle of the cylinders casting, be- 
tween the cylinders and the smoke-box. The steam-chest is 
bored out, and a bushing with accurately machined ports is 
forced in. The valv^e, shown in half-section in Fig. 29, is of 



IMPRO VED SLIDE- VAL VES. 



55 



the piston type — double and hollow — and it controls the 
admission and exhaust of both cylinders. The pistons — 
secured to a common cros^ead — move in unison ; and the ex- 
haust steam from the^high-pressure cylinder, becoming the 
supply steam for the low-pressure cylinder, is conveyed from 
the high-pressure port through the hollow valve to the low- 
pressure port at the opposite end. The operation of the valve 
can be readily understood by considering it as two valves com- 
bined — one for the high-pressure cylinder ports, and a shorter 
one for the low-pressure 
ports. The valve is 
shown in its central po- 
sition ; and it will be 
seen that the laps are 
equal, and that steam is 
admitted over outside 
port edges and expelled 
over inside port edges. 
Live steam is conducted 
to both ends of the valve- 
chamber, and is finally 
exhausted in the central 
cavity, which connects 
with the exhaust-pipe. 
There is negative lap on the exhaust side, and the steam will 
be released in the high-i:>ressure cylinder before it is admitted to 
the low-pressure cylinder. In the meantime it is stored in the 
hollow valve-body, which thus serves as a receiver, and makes it 
practicable to use admission lap for the low-pressure cylinder. 

In locomotives it is necessary to restrict the exhaust outlet 
in order to get the benefit of expansion in the smoke-box, and 
the back-pressure tends to increase the compression in the low- 
pressure cylinder ; an early exhaust closure is, therefore, not 
desirable, and it is avoided by means of a negative exhaust lap. 




Fig. 28. 



dQ 



THE SLIDE-VALVE AND ITS FUNCTIONS. 




LOW-PRESSUBET CYLINDER 

Fig. 2g. The Vauclain Valve. 

On the high-pressure side the exhaust lap is also negative, for 

otherwise the density of the receiver-steam would bring the 

compression up too high. It is not necessary to cut off earlier 

than half-stroke, for this gives six 
p. 

nominal expansions ; and thus a larger 

port-opening and more decisive cut- 
off action is incidentally gained by 
compounding. 

A reduced indicator diagram is 
shown in Fig. 30. The point of re- 
lease is easily discernible in the high- 
pressure diagram, and it will be 
noticed that the expansion is checked before the low-pressure 
port is open. This is not remarkable, considering the small 




.H.P. 1370 

Fig. 30. 



capacity of the receiver. 



IMPROVED SLIDE- VAL VES. 



57 



THE ALLFREE VALVE-GEAR. 



/ 



There are severaj/ well-founded objections to the use of a 
single valve in variable cut-off engines and locomotives. The 
small port-opening, the slow cut-off action, the early release, and 
the extremely variable compression are not desirable features. 
There are various valve-gears in use, which give ample port- 
opening, but they do not correct the premature release and 
early exhaust closure. The ordinary valve-motion, when cutting 
off at half-stroke, is represented in diagram 31. As explained 
in chapter i, the two lap lines must 
be parallel ; and arcs 4-6 and 1-9 
must, therefore, necessarily represent 
equal intervals of time, that is, the 
interval between cut-off and release, 
and between exhaust closure and ad- 
mission, must, under all conditions, 
be equal. When the valve cuts off 
at half-stroke, the release and com- 
pression may be quite satisfactory ; 
but at earlier cut-off, when the full 
benefit of expansion is obtained, the 
exhaust action becomes less satisfac- 
tory. The compression may not be- 
come excessive if there is considerable clearance ; but the vari- 
ableness of the compression is unavoidable ; and it may safely 
be assumed that much clearance is not conducive to steam 
economy. 

If the exhaust-cord would remain as sho^vn in Fig. 31, a 
small clearance would suffice, and the release would be satisfac- 
tory. Practically, these are the conditions existing in the All- 
free single-valve engine. The valve-gear is shown in Fig. 32. 
There are a toothed sector, a pinion, and a small eccentric 
mounted in the rocker-arm. While the rocker-arm is actuated 




68 



THE SLIDE-VALVE AND ITS FUNCTIONS. 




in the ordinary manner from 
the governing eccentric, the 
sector is operated from a fixed 
eccentric keyed upon the shaft. 
By this means a rotary motion 
is imparted to the pinion-shaft. 
This shaft is made from a soUd 
piece of machinery steel, having 
an eccentric of about |'' radius 
formed at one end. This eccen- 
tric is connected through a small 
link to the valve-stem. In oper- 
ation, if the rocker arm is allowed 
to stand fixed, and the engine 
rolled over, the eccentric on the 
pinion-shaft would move the 
valve three-fourths of an inch. 
If the rocker arm is allowed to 
operate, the small eccentric will 
make nearly a whole turn while 
the rocker moves from one ex- 
tremity of its throw to the other ; 
and it will be clear that, during 
the rotation of the eccentric, and 
the movement of the rocker arm, 
at certain predetermined points 
the two movements will coincide 
and others will oppose. It gives 
the valve a high speed at the 
time of opening and closing, and 
a slow speed or pause during ex- 
pansion. Thus the valve is 
caused to open for a given cut- 
off about twice as wide as in an 



IMPROVED SLIDE-VALVES. 59 

ordinary automatic. The advantage thus secured for the steam 
admission is likewise soured for the exhaust. 

In Fig. 33 let the^^ain eccentric be held by the governor in 
position B for latest cut-off, and let E mark the position of the 
fixed eccentric, theiiT angle V represents the angular advance 
of the main eccentric in relation to the fixed eccentric. When 
the main eccentric has been moved to position B' for shortest 
cut-off the angle between the eccentrics has been increased 
to 1 80°. The throw of the main rocker-arm is determined by 
the throw of the main eccentric, and the rotation of the small 
rocker-eccentric is determined by the relative position of the 
two eccentrics on the shaft. Therefore, in proportion as the main 
eccentric is advanced toward the 

crank the motion of the rocker- ^"^^^^ ^\ 

eccentric becomes later relative /^\ >v 

to the rocker motion. Now the / ', V~^x \ 

rocker-eccentric may be placed in crank ( / \ ^ ^^ I ci 

any desired position in relation to T ^ i 

the rocker, and it may be so put \ / 

that when the valve is cutting off \v ^ 

at half-stroke release and exhaust 
closure will be timed just as with ^^' ^^* 

an ordinary valve-gear ; but when the governor eccentric is 
moved forward the rocker-eccentric will lag behind to the same 
extent, and the whole series of alternatingly increased and 
diminished valve movements will occur a little later in the 
stroke. The effect of this will be to lengthen the interval be- 
tween cut-off and release, and to shorten it between exhaust 
closure and admission ; and this is just what is needed in order 
to get a later release and less compression, and thus the ideal 
conditions represented in Fig. 3 1 may be nearly realized. 

Fig. 34 represents an indicator diagram from the Allfree 
engine. It will be recognized as a remarkable single-valve dia- 
gram, and further comment is unnecessary. 



60 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



The valve, Fig. 32, is in the shape of two circular segments ; 
it is extremely light, and is balanced between an arched hood 
and the valve-seat. Steam is admitted to the inside space, and 
it partly surrounds the cylinder. The large port-opening obtain- 
able with the Allfree valve-gear obviates the necessity of com- 
plementary ports, and the steam-passages being direct and very 
short, the clearance is reduced to a minimum. It will be ob- 



Engine 7 x 12 
Rev. 220 

Spring 50 




Fig. 34- 

served in Fig. 32 that the weight of the valve is carried by a 
long adjustable bracket bearing, which keeps it from bearing 
on the hood. 

This valve-gear may be used on any single-valve engine 
whether steam is admitted inside the valve between the ports 
•or on the outside ; in either case the fixed eccentric will be 
placed in line with the crank and on the opposite side of the 
main eccentric. 



FOUR-VALVE SYSTEMS. 61 




CHAPTER IIL 

FOUR-VALVE SYSTEMS. 
INTRODUCTORY REMARKS. 

Four separate valves are often used, two at each end of the 
cyhnder, one for steam and one for exhaust. If all four valves 
were positively driven by one eccentric the steam distribution 
would be exactly like that of a common D-valve — it would, in 
effect, be the D-valve dissolved in its four component parts. 
But the four-valve system has points of superiority not possessed 
by the single combination valve. 

1. Steam and exhaust passages become short and direct. 

2. The valves are not balanced ; but the unbalanced pressure 
will only be that due to the difference between the pressure in 
the cylinder and that in the adjoining steam and exhaust cham- 
bers, and the full effect of this will be intermittent, and on the 
port area only. 

3. The separation of the valves makes it possible to reduce 
the valve motion by means of toggle motion of the valve rods. 
The port must be covered during one-half the period of revolu- 
tion at least, and if the motion of the valve is the same in oppo- 
site directions from a central position, as it must be with the 
D-valve, the greater part of the motion must generally occur 
after the port is closed, This can be avoided when the valves 
are separate, for then each valve may be separately attached to 
a special rocker or wrist-plate in a manner to produce a reduced 
valve-motion during the closed period. 



62 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



CORLISS VALVES. 



Fig. 35 represents diagrammatically the Corliss valves and 
wrist-plate connections for one end of the steam cylinder. It 

shows how the toggle 
motion of the radius- 
rods operates to shorten 
the movement of the 
valve after the port is 
closed. As the angular 
motion of the valve is 
reduced by the toggle 
action, it becomes pos- 
sible to use smaller 
valves than otherwise 
practicable, because a 
given angular motion 
yields a larger port- 
opening than could be 
had with a straight mo- 
tion of the rod. 
Figs. 36 and 37 show the construction of the first Corliss 
valves. The valve stem has a flat extension which fits the 
whole length of the valve, and has a journal at each end. 

The Corliss steam- 
valve, shown in Fig. 38, 
is a simple circular slide 
suitably guided. The slide 
and cylindrical parts at 
each end are now often 
cast in one piece, and the '^^' ^^ ^^* 

valve-stem terminates in a T-head which fits in a slot across 
the end of the cylindrical part. 

These valves are often made double-ported to avoid the 




Fig. 35- 




FO UR- VA LVE S YS TEMS. 



63 



necessity of using large diameters or to reduce the motion. 
The objection to double ports is the increased clearance space 
they make. The clearance may be re- 
duced to a minimpm by putting the 
valves in the cylinder heads, and this 
would, no doubt, become the general 
practice if it did not involve somewhat 
complicated steam connections. 

Double-ported steam and exhaust 
valves are shown in Fig. 39. Fig. 40 
represents three-ported valves for the 
lower head of a 60-inch low-pressure cyl- 
inder of a cross-compound vertical engine, designed by Messrs. 
Rice & Sargent. The steam-valve is held up to its seat by end- 




Fig. 38. 




Fig. 39. 



64 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



gibs, supported by flat steel springs, and these are adjustable by 
means of screws from the outside. 

The exhaust-valve is a hollow shell with closed ends. It is 
separated from the bottom of the cylinder by a loose ported 
valve-seat plate, the upper side of which is flush with the cylin- 
der head. This plate is held freely between planed jaws in the 
cylinder head ; and the steam pressure in the cylinder keeps it 
against the valve, and prev^ents the steam from passing inside 
the valve when the ports are closed. The opposite side of the 
valve is provided with a single wide port, and is always open to 
the exhaust-chest. This construction gives less clearance than 
the ordinary Corliss exhaust valve. 




Fig. 40. 

The operation of the Corliss induction valve is quite different 
from that of a common slide-valve. The special feature is a 
disconnecting device, which allows the valve to be closed by a 
spring or vacuum dash-pot, or other independent agency. The 
eccentric moves the valve till it is released by the knock-off 
cam, and it is then closed by the dash-pot. The valve is per- 
fectly at rest during the expansion period and the greater part 
of the exhaust period, but during the exhaust period it is caught 
by the *' steam-hook," and slowly started, so as to admit steam 
near the beginning of the forward stroke. The amount of 
opening and the period of admission depend on the position of 
the knock-off cam, and this is in turn determined by the speed- 



FOUR-VALVE SYSTEMS. ^b 

reoTulator. When the steam-hook arm strikes the knock-off cam 
the hook is released, and the valve is closed by the dash-pot. 
The result is a nearly id^al valve-motion. 

LIMITATIONS OF THE CORLISS GEAR. 

When a single eccentric drives both steam and exhaust valves 
the range of cut-off is limited to about half the piston-stroke. 
This will become obvious by considering the following necessary 
conditions : 

1. After the eccentric has reached the extreme of its throw 
in either direction all valve-gear motions are reversed. 

2. The steam-valve must be released before the eccentric- 
motion is reversed, for if the hook does not strike the knock-off 
cam during the forward motion it cannot strike it during its 
return motion. 

3. The maximum exhaust opening, or the middle of the 
exhaust period, must occur when the eccentric is at the end of 
its throw. 

Now, in order to get release of the expanded steam in the 
cylinder before the commencement of the return-stroke and 
exhaust-closure a little before the end of the return-stroke, the 
middle of the exhaust period, or the extreme throw of the ec- 
centric must evidently occur before the middle of the return- 
stroke ; and therefore the extreme throw of the eccentric in the 
opposite direction must occur before the middle of the forward 
stroke, and the valve must be released before that point is 
reached, if released at all. 

The point where steam is cut off is not coincident with the 
action of -the cut-off cam, for it takes some time to close the 
valve. With a long piston-stroke the closing period is compara- 
tively short, but it is far from being ''instantaneous," as seems 
to be the prevalent impression. The return-motion of the valve 
and dash-pot starts comparatively slow, as indeed all motion does ; 
but this slow motion is not observable on account of the short- 



66 THE SLIDE-VALVE AND ITS FUNCTIOXS, 

ness of the interval, and by overlooking this fact a false concep- 
tion of the dash-pot action is formed. 

A good vacuum dash-pot closes the valve in about one-six- 
teenth of a second at late cut-off, or during one-twelfth of a 
revolution if the engine makes eighty revolutions per minute; 
and the closing motion will in that case cover about one-sixth of 
the stroke. With short stroke and high piston-speed the latest 
cut-off would be much later than mid-stroke. 

The releasing gear is seldom used on high-speed engines, be- 
cause the sudden and frequent action will cause it to wear quick- 
ly and become unreliable ; and, as a sharp cut-off is not attainable 
at high speed, there is not sufficient justification for the use of a 
somewhat complex and delicate gear. One hundred revolutions 
per minute may be assumed as a practical limit for the Corliss 
gear. 

This speed-limit of the Corliss gear is of no consequence in 
connection with large engines, where great piston-speed may be 
obtained with less than one hundred revolutions per minute ; 
and, for obvious reasons, in such cases simplicity or fewness of 
parts is a consideration of less moment. 

It will be understood from the foregoing that late release and 
late exhaust closure are conditions imposed by the single-eccen- 
tric-valve gear ; and these conditions agree very well with moderate 
piston speed, but at higher speed earlier release and more com- 
pression may be required. 

This may be effected by moving the eccentric forward on 
the, shaft; but the reversing of the steam-hook motion would then 
also occur at an earlier stage of the forward stroke, and the range 
of cut-off would be correspondingly shortened. 

Earlier exhaust closure could be had by giving the exhaust- 
valve more lap, but this would involve a later release of the ex- 
panded steam at the end of the forward stroke. On the other 
hand, shortening the exhaust-lap would give earlier release, but 
insufficient or no compression. 



FO UR- VAL VE S YS TEMS. 



67 



THE SINGLE-ECCENTRIC VALVE DIAGRAM. 

Let the circle, Fig. 4/, represent the path of the center of the 
eccentric turning in the direction shown by the arrow, and let 
the horizontal diametbi^ represent the throw of the eccentric. 
When the center of the eccentric is at point i the steam-port 
opens, and if the valve is not released before the end of the 
throw at point 3, the port will close again at point 4. The 
exhaust-port opens at point 6, and is closed at point 9. The 
crank is supposed to be at its dead center C when the eccentric 
is at point 2, just after opening the steam-port. When the crank 
is on the opposite dead center, the eccentric must be at point 
7, diametrically opposite point 
2 ; and the point of release at 
6 occurs a little before this, 
as it should do. Arc 1-2 
represents period of steam- 
lead, and arc 6~J represents 
period of exhaust-lead, and arc 
9-1 represents the compres- 
sion period. When the ec- 
centric is at point 3, the valve- 
gear motion is reversed, and 




Fig. 41. 



the crank has not yet arrived at point 10 ; the valve is, there- 
fore, necessarily released before mid-stroke, if it is released at 
all. Note that the chords must be parallel if there is only 
one eccentric, and that in order to get release before the end 
of the stroke, the diameter 2-7 must cross the chord 6-9, If, 
in order to extend the cut-off, point 2 be moved back to point 
10, the diameter 10-5 could not be made to cross the exhaust 
chord in any position, and release would then take place after 
commencement of the return stroke. This simple diagram fully 
illustrates the hmitations of the single-eccentric valve-gear ; but 
it may be profitable to turn the figure, and let diameter 2-7 



68 THE SLIDE-VALVE AND ITS EUNCTIONS. 

represent stroke of the piston, and let the chxle represent 
the path of the crank. Points i, 2, 3, . . . will then mark sig- 
nificant positions of the valve-gear in proper relation to the 
piston-stroke, and an imaginary indicator-diagram may be con- 
structed, as shown. Note that by this arrangement the position 
of the eccentric relative to the crank is not considered ; but it 
clearly shows the result when the eccentric is moved forward on 
the shaft, in which case the whole cycle of events occurs earlier 
in the stroke ;.that is, the lead is increased, the range of the cut- 
off is diminished, and there will be earlier release and more com- 
pression. 

The steam-hook connects with the valve at or near the 
extreme of its throw ; and the eccentric-motion 8-1 determines, 
therefore, to what extent the valve must overlap the steam-edge 
of the port when at rest. Note that during this period the valve 
should move as little as possible (8-1 Fig. 36), and the radius- 
rod must therefore have considerable lateral motion before the- 
valve opens. 

When the wrist-plate is in its central position the eccentric is 
at point 10, and the lap of the steam-valve in this position is de- 
termined by the eccentric-motion lo-i. The corresponding 
exhaust-lap is determined by the eccentric-motion 5-6. The ex- 
haust-chord 9-6 could evidently be moved to the other side of the 
center, in which case the exhaust -valve would not cover the port 
at half -throw ; or the chord could be placed centrally, which would 
make the exhaust-period cover exactly one-half revolution, and 
would put the exhaust-edges "line and line" in the half -throw 
position ; but such changes would give earlier release and less 
compression. Lap or clearance can be laid out very accurately 
on the drawing-board, and it should be marked on the drawing. 
The great adjustability of the Corliss gear makes it easy to set 
the lap by some rule of thumb after the engine is erected, and a 
little variation in the points of release and compression may not 
be of much practical consequence ; but when a "good " indicator- 



FOUR-VALVE SYSTEMS. G9 

card is required there may later be some tedious resetting to do. 
There should always be marks at the end of the valve, inside 
the rear-bonnet," in line ,^th the steam-edges of valve and valve- 
seat. / 

At point 3 the motion of the steam-hook is reversed ; and if 
arc 3-P represents the period of dash-pot movement, arc 2-P 
will represent the admission-period for latest cut-off, as deter- 
mined by the knock-off cam, which, in this case, would be one- 
quarter of a whole revolution or h^lf of the piston-stroke ; but if 
under heavy load, the speed-regulator puts the knock-off cam out 
of reach of the steam-hook, the engine will take steam during 
period 1-4, or nearly full stroke. 

TWO ECCENTRICS. 

In order to obtain a greater range of cut-off in Corliss 
engines, a separate steam-eccentric is used and has become quite 
common. With two eccentrics the admission and exhaust-peri- 
ods can be adjusted independently, and steam may be cut-off 
anywhere, nearly to the end of the stroke. 

In order to start the valve without shock, the hook must 
connect with it when near the end of its throw ; and the steam- 
eccentric may be so placed in relation to the crank, that this 
connection is made near the end of the return piston-stroke, for 
the valve need not overlap the port more than from one-half to 
three-fourths of an inch when closed. 

The arrangement of steam-rods exemplified in Fig. 35, 
is in every respect satisfactory in connection with a single- 
eccentric valve-gear ; for in that case a slow initial valve-motion 
is imperative, and it is obtained by the lateral movement of the 
radius-rod. But with two eccentrics a quicker initial motion is 
feasible and desirable, and it may be obtained by- reversing the 
valve-motion and admitting steam over the top of the valve 

(Fig. 39)- 

Separate eccentrics require separate wrist-plates, and their 



70 



THE SLIDE-VALVE AND ITS EUNCTIONS. 



centers may be located one above the other, as shown in 

Fig. 39- 

Figs. 42 and 43 show how the eccentrics may be placed on 
the shaft. The steam-eccentric is at point 2, Fig. 42, and the 
exhaust-eccentric is at point E, Fig. 43, and the crank is at its 
dead center at C. Individual eccentric circles are shown for 
the sake of clearness, and the notation is the same as in F'ig. 41. 
An imaginary motion of the eccentric-arm will point out the 
various events. Referring to Fig. 42, near point 8, at the 
extreme of the throw, the hook connects with the steam -valve, 
and at point i the steam edges are on the point of separating, 
and the eccentric-motion, 8-1, determines, therefore, the initial 

PC 





American Machinitt^ 



Fig. 42. Fig. 43. 

valve-motion. When the eccentric is at point 2 the crank is at 
its dead center, as shown. At point 10 the steam-wrist-plate is 
in its central position, and in that position the valve does not 
cover the port, as with the single-eccentric gear ; but the port is 
open to a certain extent, determined by the eccentric-motion 
I- 10. Point 3 marks the extreme of the throw, and the corre- 
sponding position of the crank is at C, at about three-quarters 
of the piston-stroke, and the limit of automatic cut-off is a little 
later. If the hook does not strike the knock-off cam the valve 
will remain open till closed by the return stroke of the eccentric 
at point 4, near the middle of the return piston-stroke. 

The exhaust action is discernible from Fig. 43. It is simi- 
lar to the single-eccentric action, but with this difference, that 



FOUR-VALVE SYSTEMS. 71 

the release, at point 6, occurs at about 90 per cent of the pis- 
ton-stroke, and the exhaust is cut off at about 70 per cent of 
the return-stroke, at poitit 9. The motion of the exhaust-valve, 
after it has closed the port, is determined by the eccentric- 
motion 9-3-6, and i^oll port-opening is obtained by the eccen- 
tric-motion 6-8. The motion 9-10 determines the exhaust-lap 
when the wrist-plate is in its central position. 

A valve-gear designed to be operated by a single-eccentric 
cannot very well be made to cut off much later than at half- 
stroke, even when a separate exhaust eccentric is added. For 
the slow initial valve-motion requires at least half the throw of 
the eccentric, and the other half is not sufficient for a late cut- 
off ; and it will readily be seen from an inspection of Figs. 35 
and 39 that a quicker initial valve-motion in Fig. 35 would in- 
volve radical changes in the valve-gear. However, the range of 
cut-off may be increased some by moving the eccentric back, 
sacrificing the lead ; and to this there is no objection when it 
does not involve later release. 

The advantage gained by a second eccentric would consist 
in more compression and earlier release. 

CORLISS VALVE DIMENSIONS. 

The steam- and exhaust-ports of Corliss engines are usually- 
made as long as the diameter of the cylinder-bore, and steam- 
and exhaust-valves are usually of equal diameters, but these 
diameters do not vary as the bore of the cylinders, as might be 
anticipated. The proportion varies from one-third of the bore 
in small engines to one-sixth for large low-pressure cylinders. 
The port is not necessarily proportioned according to the diam- 
eter of the valve, but the port-opening will be nearly so. It is 
considered a safe rule to make the width of port sufficient to 
allow a mean velocity of 8000 feet per minute of the enter- 
ing steam, and 6000 feet per minute of the exhaust ; but a 
smaller port area may consistently be allowed for large cylin- 



72 THE SLIDE-VALVE AND ITS FUNCTIONS. 

ders. The port-opening is in proportion to the travel of the 
valve, which is practically limited by the diameter. 

DIRECTIONS FOR SETTING THE VALVE-GEAR. 

Adjust length of eccentric-rods to give wrist-plate equal 
travel on both sides of center-mark on bracket. Adjust length 
of radius-rods to give proper lap with wrist-plate in its central 
position. Move wrist-plate to end of its travel either way (as 
marked on the bracket), and adjust length of drop-rods to let 
the hooks freely engage the catch-blocks. Put crank on dead 
centers, and set eccentric ahead of the crank, sufficiently to give 
the proper lead. Raise governor to highest working position, 
and adjust length of rods so that the knock-off cams will just 
keep the hooks off the catch-blocks ; or some initial motion 
may be allowed, but not enough to open the port. 

VALVES OF THE PORTER-ALLEN ENGINE. 

An interesting instance of the four-valve system is found in 
the Porter-Allen engine. There are two steam-valves on one 
side of the cylinder, and two exhaust-valves on the other side, 
and the valves move in a direction parallel with the cylinder- 
bore. The valves are flat ; and the steam-pressure on opposite 
valve-faces is absolutely balanced by means of pressure-plates 
which fit closely against the back of the valve, and the steam- 
passages to and from the cylinder are short and direct. The 
valves are driven by an Allen link, and the position of the 
link-block is automatically changed by a Porter governor. The 
period of admission is changed by varying the travel of the 
valve, while the lead remains constant ; and the result is the 
same as what may be accomplished by a shifting eccentric and 
a shaft governor. The exhaust-valves are driven from a fixed 
point on the link, and they have an invariable motion, precisely 
as the motion derived directly from an eccentric fixed on the 
engine-shaft. The steam valves have separate valve-stems ; and 



FOUR-VALVE SYSTEMS. 



i6> 




they receive their motion from two bell-crank levers, which, like 
the Corliss wrist motion, greatly reduce the movement of the 
valve after it has closed the port. 

Fig. 44 shows a horizontal section through cylinder and 
valves ; and it shows the course of the steam through four open- 



74 THE SLIDE-VALVE AND ITS FUNCTIONS. 

ings into the steam-port, and also from the exhaust-port into the 
exhaust-chest. Tlie pressure-plates are arched so as to make 
them practically unyielding to steam-pressure, and there is left 
a free passage for steam through the opening of the arch. The 
pressure-plates of the admission-valves are adjustable to more 
or less close contact with the valve by means of short inclines, 
against which they are held by the steam-pressure in the steam- 
chest. They are adjusted by a short lateral displacement on 
said inclines by means of screws, which extend through the bot- 
tom of the steam-chest. The pressure-plates of the exhaust- 
valves are bolted to their seats. The valves are formed like 
open rectangular frames ; and the opening in the frame is made 
wide enough to reach the edge of the valve-seat when the port 
opens, otherwise there would not be four simultaneous port- 
openings. The space inclosed by the valve-frame adds to the 
cylinder clearance ; and as the valve is perfectly balanced the 
main object of the bell-crank levers is, apparently, to shorten the 
valve and limit the clearance space. As the steam-valves do 
not move in unison, each vah^e must have its individual valve- 
stem, the stem of the rear valve passing through the front valve. 
The exhaust-valves have no lap ; that is, in its central position 
the exterior edge of port and valve are ''line and hue." The 
valve, therefore, opens and closes quickly, and only a short travel 
is required. It is obtained by means of a double-ended redu- 
cing-rocker, from the short arm of which motion is imparted 
directly to both exhaust-valves. 

Fig. 45 shows one of the exhaust -valves used on the first 
Porter-Allen engine. There is no pressure-plate ; but an open 
frame, of nearly same size as the valve-frame, is held against the 
back of the valve, as shown. This frame is bolted to a copper 
diaphragm, which is clamped to the steam-chest cover ; and the 
steam from the cylinder, having access to the back of this dia- 
phragm, keeps the frame against the valve and holds it to its 
seat. During the exhaust period this valve is absolutely bal- 



FOUR-VALVE SYSTEMS, 



75 



anced ; and the pressure during the admission period, when a 
tight joint is needed, is not excessive. There is a projection on 
the chest-cover, whirfT nearly fills the space inside the valve- 
frame, and thus the clearance was reduced as much as pos- 
sible. ( 




Fig. 45. 

The valves and valve-gear of this engine are the invention ot 
John F. Allen, and in the history of engineering will hold a 
prominent position, not only on account of their originality and 
excellency, but because they first made high speed in a variable 
cut-off engine practicable. 



GRIDIRON VALVES. 

Flat multiported, or '^gridiron" valves, Fig. 47, are often 
employed as a means of obtaining sufficient port-opening by 
short-valve travel, and they have lately been extensively used 
on four-valve engines. Flat valves are better adapted for multi- 
porting than Corliss valves. They give straight steam-passages, 
and they can readily be fitted with removable seats of hard, 
close-grained iron ; which is of some importance for high-duty 
engines under high steam-pressure, and the accurate spacing 
and finishing of the ports is more readily obtainable than with 



76 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



valve-seats cast on the cylinder. These valves have also con- 
siderable bearing surface, equally distributed, and they can be 

forced from their seat 
when much water is car- 
ried into the cylinder. 
Some offset to these ad- 
vantages is found in the 
fact that the bars of the 
exhaust-valve and the 
steam-valve-seat expose 
considerable suiface to the 
entering steam. The short 
travel of multiported valves 
Fig. 46. The Hill Valves. ig ^n advantage, if not a 

necessity. It is also a matter of convenience, for it provides 
for a valve operating mechanism of practical construction and 
of moderate proportions. 




THE HILL VALVES. 



A unique combination of gridiron valves, designed by Mr. 
Edward K. Hill, is represented in Figs. 46 and 47. The main 




Fig. 47- 
characteristics of this system is apparent from Fig. 46, which 
represents a cross-section through a pair of valves and valve- 
seats. A is the inlet-valve, which controls the admission and 



FOUR-VALVE SYSTEMS 77 

cut-off, and B is the exhaust-valve. Both valves are seated in a 
round, open cast-iron plug, of a hard, close-grained mixture, of 
which Fig. 47 is a lop^itudinal section, exposing the face of the 
exhaust-valve. The^ plug containing the valves is pushed in 
endwise, and is k(ept in place by a single nut, as shown ; and it 
may be removed and replaced very quickly — a feature which 
practical enginemen will appreciate. The valve-moving mechan- 
ism (not shown) is attached to the front end of the plug, and • 
contains a pair of toggle-levers, by which the exhaust -valve is 
moved endwise, and which leave it nearly stationary between 
the exhaust periods. The inlet-valve is worked by an oscillating 
pusher, which engages an adjustable tappet on the valve-stem. 
The pusher is below the valve-stem ; and at a certain point of its 
forward and downward movement it leaves the tappet, and the 
valve, being released, is quickly closed by a helical spring assisted 
by the steam-pressure on the valve-stem. The point of cut-off 
is changed by vertical adjustment of the tappet, and which is 
accomplished automatically by a concave lifting cam, operated 
by the governor. To prevent concussion by the closing of the 
valve, there is a dash-pot in the head end of the bracket, at the 
end of the valve-stem. It will be observed that this combination 
embodies the fundamental principles of the Corliss-gear, though 
there is no apparent similarity in the construction. The valves 
— one pair at each end of the cylinder — are driven from eccen- 
trics on a revolving shaft, which runs alongside the cylinder, and 
which also drives the governor. There is an eccentric for each 
'alve ; and the range of cut-off is, therefore, not restricted in 
any degree, and the adjustability for lead, release, and compres- 
sion is practically unlimited. The peculiar releasing mechan- 
ism and the short travel make a speed of 150 revolutions per 
minute practicable. 

The peculiar construction of these valves permits of both 
valv^es being placed directly under the cylinder, which makes 
Jess clearance than with two separate steam-passages at each 



78 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



end of the cylinder ; and this location of valves affords a nat- 
ural drainage from the cylinder ; and the steam inlet, acting 
somewhat like a separator, will serve to precipitate the water. 
Being stowed between the valve-seats, it is left in position to 
be swept away by the exhaust without entering the cylin- 
der. It can hardly be disputed that the proper place for the 
valves is directly below the cylinder-bore ; and it is, no doubt, 
practical difficulties which have prevented such disposition of 
the valves from becoming more general. The system here de- 
scribed apparently solves the problem without a drawback ; for 
the valves are readily accessible without any bolted joints, and 
there is no interference with steam- and exhaust-passages. 

According to the builders, this system is the outgrowth of 
the Wheelock system, which it has now entirely superseded ; 
and a comparison of the two systems becomes, therefore of 
great interest. 



THE WHEELOCK VALVES. 

Originally these valves were cylindrical, and semi-rotative 
like the Corliss valves ; but there is a rational, functional differ- 
ence. In the Wheelock system one valve serves for admission 

and release, and a smaller 
valve, in close proximity to 
this, cuts off the steam at a 
point determined by the 
governor ; and in that re- 
spect the system differs 
from all others described so 
far, and it belongs properly 
in the independent cut-off 
Fig. 48. The Wheelock. system, fully discussed in 

the following chapter. These valves were supported by 
hardened steel trunnions in hard bushings, which partly relieved 
the pressure on the valve-seat ; and the valve being tapered,. 




FOUR- VALVE SYSTEMS. 79 

the working faces were brought into close proximity by proper 
end-adjustment. Under moderate steam-pressure the contact 
will be light ; but, obvio^ly, this mode of balancing is not satis- 
factory under very high pressure, for the valve being supported 
at the ends only, the^eflection in the center will cause it to 
bear hard on the valve-faces ; and as the valve-barrel cannot 
readily be lined, the wear of the central portion may become 
quite considerable. 

Fig. 48 represents a section through the valves. A is the 
main valve, and B is the cut-off valve or wiper. It will be no- 
ticed that the main valve has a large exhaust- cavity, and is really 
a cylindrically formed D-valve. The exhaust-cavity greatly 
increases the unbalanced area, and it weakens the valve-body ; 
and the travel becomes considerable compared with the width 
of the bearing-surfaces. The cut-off valve has a cavity for 
double admission. It is worked from the main-valve lever by 
means of a Corliss crab-jaw, and it is closed by a tripping- 
mechanism under control of the governor, similar to that of the 
Corliss engine ; and the limitations imposed by this gear are the 
same as those of the single-eccentric Corliss gear. This is 
probably the only engine which has an independent cut-off valve 
worked by a Corliss releasing-gear. 

As the advantage of higher steam pressure became apparent, 
the inventor, Mr. Jerome Wheelock, changed his valves into 
gridiron valves, which he seated in skeleton plugs. 

These valves, unlike the Hill valves, were actuated sidewise 
by an inside rocker-shaft and cranks. 



80 THE SLIDE-VALVE AND ITS FUNCTIONS. 



CHAPTER IV. 

INDEPENDENT CUT-OFF. 

INTRODUCTORY REMARKS. 

It has been explained in Chapter I. how the exhaust may 
be satisfactorily regulated by separating the exhaust-valve from 
the admission-valve. Better results can be obtained by having 
two valves, one of which controls the admission and exhaust, 
while the other controls the cut-off only ; for by such arrange- 
ment larger port -opening and sharper cut-off is obtainable, while 
the points of lead release and compression are fixed. The use- 
fulness of this arrangement is somewhat limited, however, by 
the fact that ample compression and a wide range of cut-off can- 
not exist at the same time ; but this limitation would only be 
of consequence in ''high-speed" engines having considerable 
"clearance." 

Cut-off valves are slide-valves whose only function is to cut 
off the connection between the steam in the cylinder and that 
in the steam-chest before the piston has completed its stroke. 

In England, and on the Continent, they are named Expansion 
Valv^es, because, by cutting off the cylinder-steam from the 
main steam supply, they provide for expansion of the steam in 
the cylinder. When these valves came into use there were no 
single-valve automatic cut-off engines made, and effective expan- 
sion was obtained by expansion-valves only. 

The cut-off valve is auxiliary to the main valve ; it opens and 
closes a port through which the steam must pass before it 
enters the main steam-port, or cylinder-port. The function 
of the main valve is to admit and exhaust the steam through 



INDEPENDENT CUT-OFE. 



81 



the main ports, and it determines the points of admission, re- 
lease, and exhaust closure. The only absolute requirements of 
the cut-off ivalve are, that it shall open each of the auxiliary 
steam-porlj^ not later than the commencement of each piston- 
stroke, that4t shall close it again at a certain point in the stroke 
— which may be varied by hand, or automatically changed by 
the governor, — and lastly that it shall not open for steam again 
before the main valve has closed the cylinder-port. 



THE CUT-OFF VALVE ON A STATIONARY VALVE-SEAT. 

Fig. 49 shows the Gonzenbach cut-off. The cut-off valve 
slides on a ported partition above the main valve ; and the steam, 
after passing into the lower steam-chest, is admitted through 
either one of the 
c y 1 i n d e r-p o r t s which 
happens to be open. 
•This cut-off valve is 
double-acting — it cuts 
off by both port edges, 
moving in opposite di- 
rections — for there 
must be one cut-off for ^^S- 49- The Gonzenbach Valve. 

each stroke of the engine, twice in the period of rotation. It 
is proper to consider this valve as a pair of valves operating 
on one port, each valve closing and opening the port in turn — 
this being, in fact, a distinctive feature of the Gonzenbach 
cut-off. 

When there is a separate passage from the cut-off valve to 
each cylinder-port, steam is cut off by one of the port edges 
only. A slide of the simplest description, to cut off at one end 
of the cylinder, is shown in Fig. 50. It is shown in its central 
position ; that is, when the eccentric is at half-throw. It has 
lap, and will, therefore, cover the port entirely during more than 
half the period of rotation. Fig. 5 1 represents a cut-off valve 




82 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



with negative lap. It will cover the port during less than half 
the period of rotation. In both cases steam is cut off by edges 
A and B. The motion of these two valves is represented by 
diagrams 52 and 53 respectively. The second valve has only 





Fig. 50 



Fig. 51 



half the throw of the first one, but it yields as large a port- 
opening and a sharper cut-off. It could not be used as a main 
admission-valve, because it is open during more than half the 
period of rotation, but it is the proper construction for a cut-off 
valve. 




NEGATIVE LAP 



POINT 
OF CUT OFF 




Fig. 53 



Rg. 52 



The right-hand side, or half, of the valve of the Gonzenbach 
cut-off operates as represented in diagram 5 3, but the left-hand 
side, cutting off by the opposite port-edge, covers the port part 
of the time when it would be left open by the right-hand side 
of the valve, and vice versa. The motion diagram of this valve 
is represented in Fig. 54. Note that in this diagram the port- 



INDEPENDENT CUT-OFF. 



83 



opening is shown on both sides of the center Hne, and it should 
be measured irom one of the two lap lines toward the center 
line. The point of cut-off may be automatically varied by rota- 
tfon of the/cut-off eccentric on 
the shaft ; but in that case the 
cut-off is limited to one-half of 
the piston stroke, for the valve 
must be capable of holding the 
port open or closed in the same 
length of time, the limit of 
which, in this case, is one- 
fourth of the period of rotation. 
This valve is not used now, for 
other reasons besides its limited 
range of cut-off. The steam in 
the lower part of the steam- 
chest will expand with the 
steam in the cylinder, and under light loads the cut-off will be 
very short, and under these conditions the speed cannot be 
properly regulated by the operation of the cut-off valve. 

The cut-off valve sometimes slides on an anchor-plate which 
bears against the back of the main valve, and there are passages 
through the anchor-plate and the main valve which conduct the 
steam to each cylinder-port separately. The main objection to 
this arrangement is that the anchor-plate is unnecessary, for the 
cut-off valve may as well slide on the back of the main valve 
directly. 




Fig. 54. 



THE CUT-OFF VALVE ON BACK OF THE MAIN VALVE. 

Fundamental Principles. 

In order to fully understand the working of a cut-off valve 
on the back of the main valve certain fundamental principles 
should be well understood. First, it should be recognized that 



84 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



the action of the cut-off valve depends entirely on its motion 
relative to the main valve ; and if this relative motion can be 
represented abstractly in a simple manner any reference to the 
motion of the main valve will be useless. 

In Fig. 55 B is the center of the main eccentric, and E is 
the center of the cut-off eccentric, and these centers are con- 
nected by an imaginary straight line. The two points B and 
E form a connected system of points, which moves around the 
center A, and, at the same time, the system revolves about 

itself, or about some point in the 
system ;' thus : point B describes a 
■ circle around point A, and, at the 
same time, point E describes a circle 
around point B. Four positions of 
points B and E are shown by full 
lines, and dotted lines indicate the 
positions E would take if it did not 
revolve about B ; in which case the 
cut-off valve would evidently not slide 
on the main valve at all, and there 
would be no cut-off action. This 
action, therefore, depends on the ro- 
tation of E around B, and is not in 
the least effected by motion of B 
Fig. 55. about A ; and the relative motion 

of the cut-off valve will be as if it worked on a stationary seat, 
and was driven by an eccentric of eccentricity equal to distance 
B E. The upper circle. Fig. 55, represents the path of this 
equivalent ideal cut-off eccentric, and corresponding and coin- 
cident positions of the eccentrics in both figures are indicated 
by the notation. Note that corresponding positions of the cut- 
off eccentric arm, from B as a center of rotation in both figures, 
are parallel. When the equivalent eccentric is at mid-throw 
the cut-off valve is in its central position relative to the main- 




INDEPENDENT CUT-OFF. 



8-"> 




Fig. 56. 



valve, and if the cut-off edges were then ''Hne and Hne," the 
cut-off action would evidently be the quickest possible ; and the 
fallacy of thie common statement that the quickness of the cut- 
off is due/ to the fact that 
main- and Wat-valve move in 
opposite directions, becomes 
evident, for, as in the present 
case, the cut-off may become 
quicker if the main valve does not move at all. The superiority 
of the independent cut-off lies in the facts that no restriction of 
the main port-opening is required, and that the cut-off may 
occur when the virtual, or equivalent, cut-off eccentric is near 
the middle of its throw. 

The independent cut-off action, as compared with the single- 
valve action, is shown approximately in Fig. 56, where the 
shaded area represents the port-opening for one-quarter cut-off 
with separate cut-off valve, and the flat arc represents the 
corresponding single-valve opening. 



THE MEYER CUT-OFF. 

Fig. 57 shows the Meyer cut-off, which has been in use since 
1842. Adjustable slides work on the back of the main valve, 
and are driven by a separate fixed eccentric. The sHdes are 

shown close together, 

3) 



which is the adjustment for 
latest cut-off. A and Bare 
cut-off edges, and the dis- 
tance they are apart con- 
stitutes negative lap, which 
is called '' space." By 




AmeHcan Ma 

Fig. 57. The Meyer Valve. 



turning the screw the slides are separated -and the space is di- 
minished, which has the same effect as increasing the lap on other 
valves ; that is, it brings about an earlier cut-off. The stem of 
the screw extends through the back of the steam-chest ; and it 



86 777^ SLIDE-VALVE AND ITS FUiYCTIONS. 

may be turned, without stopping the engine, by means of a 
hand-wheel mounted on a sleeve. The main valve has an ex- 
tension on each end, which contains the passage through which 
the steam is conveyed to the main cylinder-port ; otherwise the 
face of this valve is constructed as that of a common shde- 
valve, designed to cut-off at about three-quarters of the piston- 
stroke. 



THE MEYER CUT-OFF DIAGRAM. 

The essential data required for the design of the Meyer cut- 
off mechanism, can readily be obtained by paying close attention 
to fundamental principles. ' The lower circle. Fig. 58, repre- 
sents the path of the main eccentric. At the end of the hori- 
zontal diameter, and with radius equal to the lead, make a small 



Space for 
J^ cut-off 



ment \ 




Fig. 58. 



American Machinxit 



circle, as shown, and draw a chord touching this circle, and 
whose projection on the diameter of the eccentric-circle bears 
the same proportion to the whole diameter as the distance 
traversed by the piston before steam is cut off by the main 
valve bears to the whole stroke, and which, in the present case, 



INDEPENDENT- CUT-OFF. 8T 

is supposed to be as three to four. A radius at right angles to 
this chord indicates the position of the main eccentric, B, when 
the crank i^ at its dead center at C. With a radius somewhat 
smaller than that of the main eccentric, draw a circle directly 
above, as shown. This circle represents the path of the equiva- 
lent or ideal cut-off eccentric. The extreme range of adjust- 
ment of the cut-off valve, relative to the port on the back of the 
main valve, is indicated to the left, where the cut-off valve is 
shown in its middle position, adjusted for earliest and latest cut- 
off respectively. 

First fix the cut-off position of the equivalent eccentric 
when the valve is set for latest cut-off. For reasons which 
will appear afterwards, this position should be near the ex- 
tremity of the throw ; let it be at D in the upper circle. 
When the piston has traversed three-quarters of its stroke, 
the equivalent cut-off eccentric is at D, at the instant that it 
closes the port ; and, therefore, by marking off from D back- 
wards the three-quarter stroke angle V, the point K is located, 
which marks the position of the equivalent eccentric when 
the crank is on its dead center, at the commencement of the 
stroke; and by transferring the arm BE to a parallel position 
on the main-eccentric-circle, as shown, the proper location of 
the cut-off eccentric relative to the crank-shaft is obtained. 
The speed of the engine is, in the present case, supposed to 
be regulated by a throttling governor, and the point of cut-off 
will only be varied occasionally, to suit the load or steam-pres- 
sure ; and it is, therefore, not necessary to cut off the steam 
earlier than at one-quarter of the stroke. Make angle EF equal 
to the quarter-stroke crank-angle, and F will mark the one- 
quarter cut-off position of the equivalent eccentric, and the 
distance of F from the vertical center-line gives the negative lap 
or valve-space for earliest cut-off, while the valve-space required 
for latest cut-off is given by the horizontal distance of point D 
from the center line ; and the horizontal distance between these 



88 THE SLIDE-VALVE AND ITS FUNCTIOXS. 

two points' represents the entire range of adjustment of the cut- 
off valve in the present case. If earlier cut-off is required, the 
valve-space must be made smaller. For cut-off at one-eighth of 
the stroke, the cut-off edges would coincide, and for still shorter 
cut-off, the valve would overlap the port in its midled position. 
The motion is quickest at the middle of the throw, and the 
quickest cut-off is that which occurs at or near mid-throw of 
the equivalent eccentric. The radius of the eccentric-circle 
may represent maximum speed of relative motion at mid-throw, 
and at other points it is represented by vertical ordinates to the 
horizontal diameter. It will be seen that sharper cut-off could 
be had for the entire range by moving point D farther back on 
the circle ; but this would also throw point E farther back, and 
would increase the diameter of the cut-off eccentric ; and as it 
so happens that a sharp cut-off earlier in the stroke is of more 
consequence than later in the stroke, the arrangement here 
shown is generally adopted. Thus it appears that the design 
of the Meyer valve-gear is restricted by a desire to keep down 
the size of the cut-off eccentric ; and it will also be readily 
seen that the eccentrics cannot very well be of same diameter, 
unless the range of cut-off be limited to five-eighths of the 
stroke. The latest cut-off may occur before the main port is 
closed, and in that case the short period during which the cut- 
off valve is closed, as shown on the diagram, must be taken into 
account ; for otherwise it may happen that the cut-off port is 
open again before the main port is closed. The location of the 
cut-off eccentric, when the main port is closed, is found by 
marking off the corresponding crank-angle from point E forward. 
It will probably be admitted that the graphical method here 
shown is simpler than that invented by Dr. Zeuner ; but the 
greater advantage of the method here presented lies in the fact 
that the geometrical construction is less artificial, and may 
readily be reasoned out, and may therefore be retained in the 
mind more readily than any process that must be learned 



INDEPENDENT CUT-OFF. 89 

mechanically, and which requires a somewhat complex geomet- 
rical construction which must be produced before the problem 
is considered. For the sake of simplicity and clearness, it 
seems better to use the simple Sweet diagram for the main 
valve, ahdr^treat the cut-off valve separately ; for nothing is 
gained, and much may be lost, by drawing so many lines and 
circles in one figure. It should also be considered that the 
planning of the valve motion, and not the drawing of the 
diagrams, takes the designer's time. It does not pay to rub out 
many lines and draw others in their place ; for paper is cheap, 
and the drawing of a fresh diagram requires but little time, and 
this time is of little consequence if the valve-gear to be desi^med 
is worth anything. 

LIMITATIONS OF THE MEYER CUT-OFF. 

The Meyer valve-gear is admirably adapted for hand adjust- 
ment, but the adjusting screw may be operated by the governor. 
This may be accomplished by means of a rack and pinion, but 
the motion required and the friction of the screw are unfavor- 
able conditions for a satisfactory regulation of the speed of the 
engine ; and the difficulty is increased by the fact that if the 
range of cut-off is to extend to the beginning of the stroke, 
the adjustment of the slides will be about twice that required 
if the cut-off is beginning at one-quarter of the stroke. By 
making the right-hand screw and left-hand screw of different 
pitch, the cut-off can be made to conform closely to the irregu- 
larity of the piston-motion caused by the angular motion of the 
connecting rod.* 

THE RIDER CUT-OFF VALVE. 

If the cut-off ports on the back of the main valve are made 
converging, and the cut-off edges of the valve are made to con- 
form to this, the lap or valve-space may be varied by a lateral 

* The effect of the angular motion of the connecting-rod is explained in the last chapter. 



90 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



adjustment of the cut-off valve. This principle holds if the 
valve surface is made cylindrical, in which case the valve-seat 
becomes concave, and the cut-off edges become right- and left- 
hand screw-lines of steep pitch. The adjustment for earlier or 
later cut-off is then effected by a partial rotation of the cut-off 
valve, which is done automatically by a governor of the Porter 
type, by means of a rack which engages a pinion on the valve- 
stem. This form of valve-gear was invented by A. K. Rider of 
New York, and it has been applied to quite a number of en- 
gines ; but at the present time the combination of a shaft 
governor and a single balanced valve is preferred. 

CUT-OFF VARIED BY ROTATING ECCENTRIC ON THE SHAFT. 

The cut-off valve may be a simple slide with inner or outer 
cut-off edges, driven by an eccentric loosely journaled on the 
engine-shaft and connected with a shaft governor, which auto- 
matically changes the cut-off in relation to the piston-stroke, by 
rotating the eccentric on its journal. 

Fig. 59 shows a main valve similar to that in the Meyer 
system. On the back of this valve is a slide, which cuts off 




Fig. 59. 

the steam by its outer edges. Both valves are shown in their 
central position, in order to show the lap, and the negative lap, 
or space, of the cut-off valve will be noticed. The main valve 
operates as a common slide valve, cutting off steam at about 
three-fourths of the piston-stroke. 



INDEPENDENT CUT-OFF. 



91 



Fig. 60 represents the relative motion of a cut-off valve. 
B may represent the center of the main eccentric, supposed 
stationary. Let the relative throw of the cut-off eccentric be 
represented by the smaller circle, then the point of cut-off will 
be at Dv^i-^t if the throw is increased, as shown by the larger 
circle, then the point of cut-off will be at. F. F and F mark 
different positions of the cut-off eccentric at the beginning of 
the piston-stroke. When this eccentric is in position F it will 
cut off steam at three-fourths of the stroke, and in the position 
F no steam will be admitted to the cylinder. For intermediate 
cut-offs the eccentric would be lo- 
cated somewhere between points E 
and F. Angle V measures 1 20 de- 
errees : and from E to F the eccen- 



tric moves through an angle of 



20 




degrees minus angle U or nearly 90 

degrees. It will be seen that an 

increase of the throw diminishes the 

angular adjustment. If, therefore, 

the cut-off eccentric be so located 

in relation to the main eccentric that 

1 Fig. 60. 

when it is rotated on the engme- 

shaft the distance between the eccentric centers is increased 
while the cut-off eccentric is angularly advanced, a considerable 
range of cut-off may be obtained. 

Diagram 6 r shows how to find the position of the eccentrics, 
the relative motion of the cut-off eccentric, the lap of the valves, 
etc. The lower circle represents the throw of the main eccen- 
tric, which is fixed on the shaft, and the dimensions of the 
main valve are shown by Sweet's parallel lines, which also deter- 
mine the position B of the main eccentric. The upper circles 
represent the motion of the cut-off eccentric around the center 
of the main eccentric. The smaller circle represents the relative 
throw of the cut-off eccentric for latest cut-off, D being the 



9-2 



TFIE SLIDE-VALVE AND ITS FUXCTIOXS. 



point of cut-off. Make angle D-E 120 degrees, and draw B-E 
parallel B-E in the lower figure. This fixes the location of the 
cut-off eccentric E. Draw large upper circle to make shaded 
part include a little more than 120 degrees of the circle, and 
make B-F parallel B-F in the lower figure. This determines 
the position F of the cut-off eccentric at shortest cut-off, and 

E-F is the angle it must be 
rotated on the engine-shaft. 
Note that radius B-E must 
be a little more than the neg- 
ative lap in order to keep the 
cut-off port closed a short 
time after the main port is 
closed. Angle V represents 
the range of cut-off, which in 
120 degrees of 



this case is 

crank angle, or three-fourths 

of the stroke. 

This construction gives a 
very sharp cut-off early in 
the stroke, and a large port- 
opening. The latest cut-off 
is slow, but at mid stroke it is 
very satisfactory. The cut- 
off eccentric is of about the 
^^* ^* same size as the main eccen- 

tric ; but its relative throw for short cut-offs becomes much 
greater. The cut-off is regulated by a shaft governor, and the 
greater rate of adjustment for short cut-offs is conducive to 
close regulation. 

The rotative movement E-F, in the lower figure, should 
not be greater than here shown, for otherwise it will be very 
difficult to construct connections between the governor weights 
and the eccentric, which will be durable and sufficiently effec- 
tive in the extreme positions. 




INDEPENDENT CUT-OFF. 



93 



The cut-off valve shown in Fig. 62 has considerable lap, and 
it cuts off by inside port edges. It is driven by an eccentric 
journalecT on the engine-shaft, and controlled by a shaft gov- 
ernor, identically in the manner just described. 




Fig. 62. 

The valve diagrams are shown in Fig. 63. The lower circle 
represents the path of the main eccentric, which is fast on the 
shaft, and also the circular path of the cut-off eccentric, both 
having the same throw. The crank is at its dead center, at C, 
the main eccentric is at B, and the cut-off eccentric is at E. 
This is the natural position of the cut-off eccentric relative to 
the main eccentric when the engine is not running, or before 
the governor begins to act, and when steam is cut off a little 
before three-fourths of the stroke. When the proper speed is 
attained the governor becomes active, and turns the eccentric 
forward. When the cut-off eccentric is advanced to the position 
F steam is cut off right at the beginning of the stroke, and 
intermediate positions of the cut-off eccentric cover the whole 
range of cut-off. The eccentricity of the cut-off eccentric in 
regard to the shaft is fixed, but in regard to the main eccentric 
it varies between the two extremes represented by distances 
B-E and B-F. The upper circles represent the variable throw 
of the cut-off eccentric in relation to the center of the main 
eccentric, B; the cut-off action being as if the valve-seat were 
stationary and the throw of the eccentric as represented by the 
upper circles. F marks the position for earliest cut-off, the 



94 



THE SLIDE-VALVE AND ITS FUNCIIOXS. 



crank being on its dead center, as shown in the lower figure. 
Make B-F parallel B-F, and through F draw a vertical ; this 
gives the lap of the cut-off valve. With radius B-E strike a 
circle, and its intersection with the lap-line, at D, marks the 




Fig. 63. 

latest cut-off relative to the center line of action, which is sup- 
posed to be horizontal. Draw B-E parallel B-E, and angle V 
is equal to the crank-angle at latest cut-off, that is, it represents 
the extreme range of cut-off, which in this case is a little less 
than three-fourths of the stroke. 



INDEPENDENT CUT-OFF, 95 

Point E marks the position of the cut-off eccentric at the 
commencement of the stroke, and it shoukl fall outside the lap- 
line, as (shown ; for the port should be open before the com- 
mencen^ent of the stroke. The moment the eccentric passes 
the lapUiiie steam is cut off, and the rapidity of valve-motion at 
this poiht is represented by the distance above the horizontal 
center line. At the beginning of the piston-stroke the cut-off 
action is slow, but it increases rapidly. K marks the cut-off 
at one-fourth of the piston-stroke, and at this point the motion 
is as quick as that of the Meyer cut-off, and the port-opening is 
more than four times that obtainable with a single valve. For 
very early cut-off the port-opening becomes exceedingly small, 
and for this reason a valve with negative lap is probably pref- 
erable. The small port-opening ''wiredraws" the steam, re- 
ducing the initial steam-pressure in the cylinder, and therefore, 
at very early cut-off this valve would not admit enough steam to 
run the engine alone, in other words, there would be no early 
cut-off. It is as yet unsettled whether this would be detrimental 
or beneficial to steam economy. At any rate, it will only be 
of consequence when the engine is underloaded. 

When laying out the valve-motion the following must be 
observed : The cut-off valve should preferably open the port a 
little before commencement of the stroke ; that is, point F should 
be a little above point B. The movement around the shaft 
should not exceed a certain limit, for otherwise it will be difficult 
to construct proper governor connections. The range of cut-off 
should not be much less than three-fourths of the stroke. It 
will be noticed in Fig. 62 that the tail-end of the cut-off valve 
opens the port a second time, which in no case must happen 
before the main port is closed. To guard against this a vertical 
line is drawn in the upper diagram, to the right from the center, 
at a distance equal to the tail-lap of the valve, and the intersec- 
tion of this line with the eccentric-circles shows the angle turned 
by the crank before the port is uncovered. 



•96 THE SLIDE-VALVE AND ITS FUNCTIONS. 

The great friction of the common D-valve makes it unsuited 
for single-valve automatic cut-off engines, but in combination 
with a cut-off valve it operates under different conditions. The 
pressure in the exhaust-cavity is but little more than that of the 
atmosphere, while the corresponding area on the back of 
the valve is exposed to full steam-pressure. It is, therefore, 
desirable to reduce the exhaust-area as much as possible, and to 
shorten the travel. In single-valve automatic engines, and in 
locomotives, the small port-opening by short cut-off must be 
taken into consideration, but with a fixed cut-off at three-fourths 
of the stroke the conditions are quite different. The travel can 
in that case be very short ; for the port opens quickly at the 
beginning of the stroke, and it is not necessary that it uncover 
the port entirely. The shorter travel makes it feasible to reduce 
the exhaust-cavity, and when properly proportioned the common 
D-valve with a riding cut-off will possess some points of merit 
not claimed for the balanced valve. 

GRIDIRON VALVES WITH INDEPENDENT CUT-OFF. 

Flat gridiron valves are used with cut-off valves of the same 
description. A longitudinal section through a pair of such 
valves is shown in Fig. 64. The cut-off valve is supposed to 




Fig. 64. 
be in its central position in relation to the main valve, and the 
space between the bars represents negative lap. These valves, 
cut-off by one port-edge only, which may be either one of the 
two edges. They are used in four-valve engines, and there is 



INDEPENDENT CUT-OFF. 97 

one set at each end of the cyUnder, and there can only be one 
cut-offior each rotation of the eccentric ; but the opposite edge 
of thp adjoining bar will cover the port part of the time while 
the /fiiain port is closed. This is merely incidental to this par- 
ticufer valve construction; for, it being desirable to have a great 
number of ports, the bridges are made just wide enough to 
avoid uncovering the port a second time in one stroke of the 
valve, that is, moving in one direction. The port will therefore 
not remain open as long as indicated by diagram 6i, but there 
will be a period of closed port on the right hand of the center 
of the upper circles corresponding to the period of closed port 
on the left side. The second closing will in no case take place 
before the main valve has closed the cylinder-port ; and it is 
rather an advantage to have the cut-off port closed during part 
of the exhaust period, for it may prevent leakage into the 
exhaust. 

If the cut-off must be carried as far as three-fourths of the 
stroke, and there is a rectilinear transmission from the eccentric 
to the valve, then the width of the bridges should be about two 
and three-quarter times the width of the port. There are three 
points which keep the design of these valves within narrow limits, 
viz., the size of the eccentric, the angular adjustment of the 
eccentric, and the parallelism of the eccentric-rods. If the cut- 
off is not to be later than at five-eighths of the stroke more 
satisfactory proportions and shorter travel may be had. 

BEGTRUP'S ECCENTRIC. 

If the cut-off eccentric were mounted on a journal concen- 
tric with the center of the main eccentric its relative throw 
would be constant and short, but there are great practical diffi- 
culties in the way of this scheme when applied to large 
engines. It would make a very large eccentric on a very 
large journal, and the friction and inertia would be too great 
for a sensitive governor. The bearing, movement and throw 



98 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



of the cut-off eccentric may be reduced in a practical manner 
now to be described. 

In Fig. 65 B is the center of the main eccentric, and E and 
F mark the positions of the cut-off eccentric for latest and ear- 
liest cut-off respectively. It will be noticed that the throw is 

not greatly increased in the early 
cut-off position if the eccentric 
is movable on the curved track 
E-F. It could be made so by 
swinging it from a point P ; but 
this point would be inside the 
engine-shaft, and cannot be used 
as a fulcrum. Identically the 
same motion may, however, be 
given the eccentric by suspend- 
ing it from two short links, one 
on each side of the shaft, as 
shown in Fig. 66. To bring the 
eccentric central over the shaft, 
as here shown, it will be necessary to swing it around the 
center B through an angle of 35 degrees, and this w^ill not 
alter the valve-motion if the eccentric-rod is also turned 35 
degrees from the horizontal, or if it makes that angle with the 
main eccentric-rod. To this there would be no serious objec- 
tion ; for the rod can be made short, and an angular rocker 
would transmit the motion straight to the valve. In its central 
position this eccentric becomes concentric with the shaft, leaving 
the valve stationary. The cut-off is then effected by the motion 
of the main valve only. The relative throw is considerably less 
than when the eccentric is moved around the shaft, and this 
short throw makes it suitable for multiported valves. It is not 
necessary that the cut-off eccentric be swung centrally over the 
shaft. If it is made the same size as the main eccentric the 
opening for the shaft may be to one side from the center, suffi- 




Fig. 65. 



INDEPENDENT CUT- OFF. 



99 



ciently so to make the eccentric rods parallel, and this does not 
make the throw in relation to the main eccentric any greater. 
A governor of the simplest description may be used with this 
ecc/ntric. 




Fig. 66. Begtrup's Eccentric. 



CUT-OFF WITH CONSTANT TRAVEL ON MAIN VALVE. 

The cut-off eccentric may be journaled concentric with the 
center of the main eccentric, and then the travel of the cut-off 
valve in relation to the main valve will be constant ; but this 
arrangement requires an enlargement of the cut-off eccentric, 
unless the cut-off can be worked from the end of the engine- 
shaft. 

Fig. 6j shows how a somewhat radical improvement becomes 
possible by the interposition of a bell-crank lever. It is here 
shown as applied to a vertical engine, but it is also applicable to 
horizontal engines. The crank is on its upper dead center, at 
C, and the main eccentric is at point B, which is also the center 
of the journal of the cut-off eccentric. The center of the cut- 
off eccentric is at E, and it is capable of rotative adjustment 

L.ofC. 



100 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



around B to point F. When at this point, steam is cut off right 
at the commencement of the stroke, when the crank is on its 
upper dead center, as shown ; and the latest cut-off, at three- 
quarters of the stroke, is obtained when the eccentric is swung 
back to position E. The valves are shown in Fig. ()Z ; they are 




Fig. 67. 

placed centrally in order to show their lap, but when connected 
with the valve-gear they are never in their central positions at 
the same time. The cut-off valve is actuated by a bell-crank 
lever which effects a reversal of the eccentric-motion, and so 
steam is cut off by the outer edges of the valve. The main 
valve is a flat plate with a rectangular exhaust opening in the 



INDEPENDENT CUT-OFF. 



101 



center and cut-off ports near the ends. The cut-off valve has a 
pressure balancing-ring on its back, which relieves the main 
valve/ of the greater part of the steam-pressure ; and as the com- 
pre^ion is constant a very satisfactory degree of balancing 
may DC obtained without causing the valve to leave its seat 
under any circumstance, except when forced out by a body of 
water in the cylinder. The travel of the main valve is constant, 
and the travel of the cut-off valve, 
in relation to the main valve, is also 
constant. The travel of the cut-off 
valve in relation to the steam-chest 
cover is not constant, but it will ap- 
pear from an inspection of Fig. dy 
that the maximum throw of the cut- f|^ 
off eccentric is less than the throw 
of the main eccentric. Near the 
middle of its rotative adjustment its 
throw is greatly reduced, and the 
valve could be made to stand still 
in its middle position if the radius 
of the curved path were made a 
little longer. It is noticeable that 
the shortest valve travel occurs 
when it is cutting off steam at one- 
fourth or three-eighths of the stroke, 
under which condition the engine 
is supposed to do the greater part 




Fig. 68. 



of its work. Slide-valve designs involve, to a great extent, the 
reconciliation of conflicting requirements, and absoute perfec- 
tion seems unattainable or incompatible with great simplicity ; 
but the combination here shown has many good points, and it 
would often be serviceable. 

To get the lap, etc., of the cut-off valve, draw a circle with 
radius BF, as shown, and make BF parallel BF. Draw a center 



102 THE SLIDE-VALVE AND ITS EUNCTIOA'S. 

line parallel FL, and at right angles to this two parallel lines 
through B and F in the lower circle : the distance between 
these is negative lap or valve-space, which added to the radius 
gives full port-opening, provided both arms of the bell-crank 
lever are of same length. The diameter of the smaller circle 
represents the relative motion of the valves, which is constant ; 
and the smaller part of the circle, cut off by the lap-line through 
F, represents the period during which the cut-off port is closed, 
and which should be a little in excess of the period during which 
the main port is open ; it should in this case encompass more 
than a three-quarter stroke crank-angle. As the throw of the 
equivalent cut-off eccentric is constant, and its port-opening is 
greater than its half-throw, it follows that a comparatively short 
relative motion is required, to give as much opening as the main 
valve which has considerable positive lap. An unusually large 
eccentric is therefore not needed, but it must need be somewhat 
larger than the main eccentric, unless the diameter of the shaft 
can be reduced. The main eccentric-rod is supposed to be ver- 
tical, and it is necessary that the eccentric-rods form an angle 
between them as shown, in order to get the desired valve-motion. 

THE BUCKEVE VALVE-GEAR. 

Mr. J. W. Thompson has designed a simple and ingenious 
valve-gear, which connects the motion of the cut-off valve with 
that of the main valve in such a manner that the travel of the 
cut-off valve, in relation to the main valve on which it slides, be- 
comes equal to, or proportional to, the throw of the cut-off 
eccentric, irrespectiv^e of its position relative to the main eccen- 
tric. The cut-off eccentric may, therefore, be journaled directly 
on the engine-shaft ; and the point of cut-off may be changed by 
a rotative adjustment of the cut-off eccentric (regardless of the 
position of the main eccentric), and as the throw of the cut-off 
eccentric is constant the relative motion of the cut-off valve will 
also be constant. There are two rocker-arms, one for the main 



INDEPENDENT CUT-OEF. 



103 



eccentric and one for the cut-off eccentric. The cut-off rocker 
is carried by the main rocker, and it is fulcrumed mid-way be- 
tween^tlie valve connection and the fulcrum of the main roeker. 
It is /a counter-arm rocker of same total length as the main 
rock(er ; and the lower end, to which the eccentric-rod is pivoted, 
is in Ime with the fulcrum of the main rocker : and, this being- 
stationary, it follows that any motion transmitted by the cut-off 
eccentric-rod to the lower end of the cut-off rocker appears re- 
versely relative to the upper end of the main rocker, irrespective 
of the position of the main rocker ; that is, the movement of the 
upper end of the cut-off rocker relative to the main rocker is 
equal to the throw of the cut-off eccentric ; and as both valves 
receive their motion from the upper ends of the rockers, it fol- 
lows that the travel of the cut-off valve, relative to the main 
valve on which it slides, is constant ; and that steam is cut off 
earlier or later according as the cut off eccentric is advanced or 
moved back on the shaft. 

The valve used on the Buckeye engine, in connection with, 
the compound rocker just described, is shown in Fig. 69. The 




Fig. 69. The Buckeye Flat Valve. 



body of the main valve is hollow, and two narrow cut-off valves 
slide on inside valve-faces, next to the cylinder valve-faces. The 
steam enters a hollow part of the steam-chest cover, whence it 
passes through sliding ring-joints to the inside of the hollow 



104 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



valve, and from there through the cut-off ports, over the inside 
edges of the main ports, to the cyUnder. The exhaust es- 
capes over the outside port-edges to the space surrounding the 
main valve and which connects with the exhaust-pipe. The 
main-valve stem is hollow and the cut-off stem passes through 
it. The proportions here shown are approximately correct for 
a long-stroke engine, but minor details are not shown. This 
construction has the advantage of short and direct steam-pas- 
sages and small cylinder-clearance ; and as the unbalanced pres- 
sure is quite moderate, the wear of the valve-faces cannot be of 
much consequence, and at the same time this pressure, in con- 
junction with a constant travel, insures permanent tightness — 
unless the faces are cut by solid matter carried over by the steam. 
As the hot steam inside the main valve is surrounded by exhaust- 
steam, some heat may be lost by reevaporation of moisture con- 
tained in the exhaust-steam ; but it is noteworthy that the 
builders have not found it necessary to make any change in this 
respect since the introduction of the valve, some twenty-five 
years ago. 




Fig. 70. 

Fig. 70 shows the principles of construction of the valve- 
gear. The center of the engine-shaft is at A, and the crank 
is on its dead center, at C. The main eccentric is at B, and 
the cut-off eccentric is at E, and the compound-rocker is repre- 
sented by two crossed lines. The lap of the main valve, its 
point of cut-off, etc., can easily be determined by Sweet's valve- 



INDEPENDENT CUT-OFF. 105 

diagram, remembering that the location of the eccentric must 
be diametrically opposite that obtained from the diagram, on 
account of the inward position of the steam-edges. The path 
of the cut-off eccentric is represented by a separate circle. 
Through the center of this circle draw a line parallel to AL ; 
and at right angles to this, in -a distance equal to half the width 
of the cut-off port, draw a chord, as shown. The distance from 
the center represents negative lap, and point F marks the 
position of the cut-off eccentric for earliest cut-off. The 
smaller arc, cut off by the chord, represents the period during 
which the cut-off port is closed ; and it is only necessary to 
observe that this port must not open before the main port is 
closed. If, for instance, the main port is closed at three- 
quarters of the piston-stroke, the cut-off valve may close the 
cut-off port a little before the commencement of the stroke, 
and keep it closed till after three-quarters of the stroke is 
traversed ; and no steam will in that case be allowed to enter 
the cylinder. 

If great accuracy is required, the varying angularity of the 
eccentric-rod may be taken into account ; and the negative lap 
or valve-space is determined accurately by drawing the lap-line 
through F at right angles to FL above, which increases the 
valve-space slightly ; but the first construction is satisfactory, 
for its error is small and on the safe side. 

PISTON-VALVES WITH INDEPENDENT CUT-OFF. 

Piston-valves of the larger sizes must fit loosely in the valve- 
cylinder, for otherwise they will occasionally become very tight. 
They are, therefore, provided with elastic packing-rings similar 
to those used on the main piston, and these rings will cause 
some wear, and if the travel is variable, uneven wear may be 
expected ; and for this reason it is claimed that piston-valves 
with constant travel wear better than those that regulate the 
steam admission by varying their travel ; and as a relatively 



106 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



constant travel is obtainable with the independent cut-off gear, 
such gear may profitably be used in connection with piston- 
valves ; and as these valves are in perfect equilibrium under 
any steam-pressure, they may have a long travel without exces- 
sive wear and without any detrimental effect on the governor ; 
and the increased travel may obviate the necessity of multiple 
ports, which in any event is of questionable utility ; for it in- 
creases the chances for leakage. 

Fig. 7 1 shows part of a piston-valve combination, adopted by 
the Buckeye Engine Company. The cut-off valve is inside 
the main valve, and the arrangement of steam and cut-off ports 
is the same as that of the flat-faced valves. Fig. 69 ; but the 
travel is longer, and the exhaust steam is discharsred at the 




The Buckeye Round Valve. 



ends, and does not come in contact with the hot surface of 
the main valve, except at the ends. The packing-rings are in 
the best possible positions to prevent leakage ; and both the 
main and cut-off ports are bridged in a number of places to 
afford ample bearing for the rings when they pass over the ports. 



CUT-OFF VALVE WORKED BY MEANS OF A LINK. 

The cut-off valve may be worked by a rocking-link as indi- 
cated in Fig. 72. In that case the cut-off eccentric E is fixed 



INDEPENDENT CUT-OFF. 



107 



on the shaft, and the travel of the cut-off valve is varied by- 
moving a block up and down in the slotted link ; which may be 
done automatically by connecting it with a governor of the 




Fig. 72. 

vertical type. By shifting the link-block the throw is increased 
or diminished, precisely as if the eccentric were shifted on a 
radial line from the center of the shaft. In Fig. 73, lower 
circle, the main eccentric ^^e lat 

is at B, and the cut-off ec- 
centric is at E, and the 
crank is at its dead center, 
at C. When the link-block 
is in its lowest position, the 
valve-motion is as if the ec- 
centric were at F and its 
horizontal motion were com- 
municated straight to the 
valve ; and shifting the link- 
block to its upper position 
corresponds to a radial dis- 
placement of the eccentric 
to point E' ; and in this po- 
sition BE' is the radius of 
the equivalent cut-off ec- 
centric, as if actuating the 
valve on a stationary valve- 
seat. With radius BF 
strike a circle, as shown above, and make BF parallel BF. 
Through F draw a line at right angles to AL, Fig. 72 ; its 




.^-p' 




Fig. 73. 



108 THE SLIDE-VALVE AND ITS FUNCTIONS. 

distance from the center determines the negative lap required. 
With radius RE' draw a circle and make BE' parallel BE' ; the 
angle V determines the range of cut-off. As the ideal eccen- 
tric is supposed to move radially, its throw in regard to its 
virtual center of revolution at B must vary considerably ; and it 
is observable that it is least near the middle of its radial path 
when steam is cut off at about one-quarter of the piston-stroke ; 
but considering that the valve has negative lap, and cuts off 
near its mid-stroke, the valve-action would be satisfactory at 
moderate piston-speed. The cut-off valve may be a plain fiat 
slide, cutting off steam by its outer edges ; and it can be con- 
structed with two cut-off edges at each end to operate on 
double-ports, though a constant relative travel is much better 
for double-ported valves. 

As here shown the maximum cut-off will be at 3-4ths of the 
stroke. Much more satisfactory valve proportions can be had 
if the cut-off is limited to 5-8ths of the stroke. 

INDEPENDENT CUT-OFF ON FOUR-VALVE ENGINES. 

TJie McIntosJi & Seymour Valves. 

Fig. 74 represents a sectional view of the Mcintosh & Sey- 
mour valves and valve-gear. There are two main valves at 
each end of the cylinder, one for admission and one for ex- 
haust. It is plain flat gridiron valves, on detachable seats, 
and they move transversely to the cylinder. 

In the valve-gear, links, which are used to transmit motion 
to the valves, are actuated by swinging rockers in such a way as 
to distort the motion *as received from the eccentric, hastening 
the movement of the valve when near one end of its stroke, and 
at the other end causing a pause in its motion, so that while a 
a rapid opening and closing of the port is secured, the valve re- 
mains practically still while closed. This feature and the large 
number of ports in the valve reduce the stroke necessary to give 



INDEPENDKiyT CUT-OFF. 



109 



full port opening to from one-half inch up to one and one-half inch 
for cylinders of the largest size ; and, since the movement of the 
valve takes place chiefly when it is open and relieved of the 
pressure of the steam, the wear and also the power required to 







Fig. 74. Mcintosh & Seymour. 

operate the valve is reduced to a small amount. And since the 
bars or bridges between ports are of same width on valve and 
valve-seat, the wear should be absolutely even on the entire sur- 
face. 

On the top of the main steam-valve is a cut-off valve, oper- 
ated by a movable eccentric, controlled by a shaft governor. 
The eccentric is journaled on the engine-shaft, and the cut-off 
is varied by varying the angular position of the eccentric in re- 
lation to the crank. The main valves are driven by a fixed ec- 
centric, controlling the admission of the steam and the opening 



110 



THE SLIDE-VALVE AND ITS FUNCIIONS. 



and closing of the exhaust. The valve-gear is simply an arrange- 
ment of links, rock shafts, and slides for transmitting the motion 
of the eccentrics to the valves. On multi-cylinder engines the 
governor usually controls the cut-off on all the cylinders. 

Valves of the Russell E7igine. 

Fig. 75 shows the valves of the Russell four-valve engine. 
There are two admission- valves, one at each end of the steam- 
chest, and on the back of these are multiported cut-off valves. 
There are two exhaust-valves of the semi-rotary kind placed un. 
derneath the cylinder, one at each end. Steam- and exhaust- 




Fig. 75. The Russell Valves. 

valves are driven by one eccentric, which is fixed on the shaft ; 
and the cut-off valves are driven by an eccentric journaled on 
the shaft and connected with a shaft governor, which regulates 
the cut-off by turning the eccentric forward or backward on the 
shaft. Fig. 'j^ shows one of the exhaust-valves. It is triple 
ported and of small diameter. As the valve-face is at the bot- 



INDEPENDENT CUT-OFF. 



Ill 



torn, it will not become leaky when worn. These valves are ac- 
tuated by means of a wrist-plate of the Corliss type, which, in 
conjunction with the multiplication of ports, makes large diame- 
ters unnecessary, and the valve cavity, or clearance, is thereby 
greatly reduced. 

The plates and springs on the back of the cut-off valves, Fig. 
75, are there to prevent the valves from leaving their seats when 
the steam-pressure in the 
steam-chest is reduced be- 
low that of the compressed 
steam in the cylinder. The 
compression of the springs 
may be increased by means 
of screws from the outside 
of the chest-cover. In this 
connection it should be 
noted that the point of ex- 
haust closure is fixed, and 
that the compression cor- 
responds to that which can 
be had at latest cut-off in a single-valve engine. It will, there- 
fore, never become excessive, but it answers its purpose when 
the cylinder clearance is sufficiently small. The valves will only 
slam when the throttle valve is closed, or when used on the low- 
pressure cylinder of a non-condensing compound engine. 

The Buckeye Vibrating Ciit-off. 

Figs. J J and J^ represent sectional front and end elevations 
of a valve-gear for large low-pressure cylinders, lately brought 
out by the Buckeye Engine Company. There are four main 
valves, two at each end of the cylinder, one for exhaust and one 
for steam. These valves are of the Gridiron pattern, and they 
move in a direction transversely to the cylinder. The steam- 
valve has a hollow cylindrical shell cast on top of it, and bored 




Fig. 76. The Russell Exhaust Valve. 



112 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



out for a pair of cut-off valves. These valves extend the whole 
length of the main valve, and they receive rotative reciprocal mo- 
tion from a central valve-shaft. Steam is admitted through 
openings in the top of the cylindrical shell, and passes through 




Fig. 77. The Buckeye Vibrating Cut-off. 

the long cut-off ports to the ports of the main valve. The mo- 
tion of the cut-off valves is similar to that of the Corliss exh-aust- 
valves. These valves are moved by an eccentric, journal ed on 
the engine-shaft and connected with a shaft governor, which 
regulates the cut-off, in relation to the piston-stroke, by rotating 



INDEPENDENT CUT-OFE. 



113 



the eccentric on the shaft. The stroke of the valves is constant, 
and earUer or later cut-off is effected by turning the eccentric 
ahead or back on the shaft. The main valve has a short longi- 
tudinal motion, derived from a fixed eccentric. It determines 
the point of admission and gives a constant lead. 




Fig. 78. Buckeye Valves. 

The exhaust-valve has an invariable motion similar to that of 
the steam-valve, and both valves are driven conjunctively by 
means of a vertical rocker shaft with short arms, which, when 
placed in their proper relative positions, will produce the toggle 
motion, by which the valve motion is retarded when the ports 
are closed and accelerated during the opening period. 



114 THE SLIDE-VALVE AND ITS FUNCTIONS. 

The cuts representing this valve-gear were reduced from 
working drawings ; and the levers and valves are, for obvious 
reasons, not shown in the relative positions they occupy when 
in operation. 

The cylinder here shown is the low-pressure cylinder of a 
tandem compound engine. The high-pressure cylinder has a 
valve of the Buckeye standard round-valve construction, Fig. 7 1 . 
The riding cut-off in this construction, as well as the vibrating 
cut-off inside the gridiron valves, are varied by angular advance 
of the cut-off eccentric, enabling both systems to be coupled to 
the same eccentric and governor. 



THE SLIDE-VALVE ON PUMPS, 115 



CHAPTER V. 

THE SLIDE-VALVE ON PUMPS. 

The common D-valve is used on the steam-cylinder of direct- 
acting pumps. In these pumps steam and water pistons, or 
plungers, are on a common piston-rod, and the steam and water 
ends are connected by a frame or bars. There are two distinct 
types of direct-acting pumps. Single Pumps and Duplex Pumps. 
They are all double-acting ; that is, steam is admitted to each 
side of the piston alternatingly. The Single style has one 
steam-cyhnder and one water-cylinder. The Duplex consists 
of a pair of single pumps of same size, placed side by side, and 
the peculiarity of this type is that the motion of each steam- 
valve is derived from the piston of the other pump. By this 
arrangement the valve-moving mechanism becomes simple and 
its action positive, and these are the main reasons why the 
duplex type has become so popular. The more uniform motion 
of the water is also in its favor. 

The slide-valve moves across the steam-ports, alternatingly 
covering and uncovering each of them ; and there is, necessarily, 
a central position where both ports are covered (or partly un- 
covered). If the valve stays in that position for a moment, the 
pump will stop ; and if the valve stops near this position, leaving 
only a small port-opening, the speed will be more or less re- 
tarded. Now this is what would happen if the valve-motion 
were derived directly from the piston of the same pump. The 
valve would slowly cover the steam-port, and finally bring the 
pump to a dead stop, before the end of its stroke. 

The means adopted to overcome this difficulty in a single 
pump consists chiefly in an auxiliary piston, located in the 



116 THE SLIDE-VALVE AXD ITS FUXCTIOXS. 

Steam-chest and called the chest-piston. This piston engages 
projections on back of the main valve, so that valve and piston 
move in unison. Before the end of the stroke of the main 
piston, steam is admitted to one end of the chest-piston and ex- 
hausted from the other end ; and this piston is consequently 
forced over to the exhaust-end, carrying the slide-valve with it. 

The steam-passages leading to the chest-piston are very 
small ; when they are uncovered the chest-piston begins to 
move, and after that the valve-motion is independent of the 
motion of the main piston, and the valve, impelled by the chest- 
piston, will now entirely uncover the steam-port for the return 
stroke of the pump. 

It will be noticed that the throttling effect of the small 
auxiliary steam-passages is of importance, for the short period 
intervening between the uncovering of the small auxiliary ports 
and the starting of the valve is essential to a successful opera- 
tion of this mechanism. The main objection is, that if any of 
the small passages are stopped up the chest-piston becomes 
inoperative: 

The inventor of the direct-acting steam-pump, Henry R. 
Worthington, found that the momentum of the moving parts of 
the engine was often - insufficient for the purpose of throwing 
the valve clear across the ports, and to accomplish this he de- 
vised a combination of a steam-valve and spring. The spring 
being compressed by the action of the engine while the valve 
remained at rest, until at the proper time, by the further action 
of the engine, the spring was released and acted upon the valve 
independently of the momentum of the engine. This device 
was patented in 1841. Several years later he used the auxiliary 
piston. 

The piston speed of pumps is much slower than that of a 
slow running steam-engine, and the steam-ports are made cor- 
respondingly small. No lap is required on the valve,'and this 
helps to reduce its travel and size. The steam-pressure ordi- 



THE SLIDE-VALVE ON PUMPS. 



117 



narily sustained by these valves is, therefore, of no consequence,, 
and the common D-form is eminently suitable for pumps. 



THE BLAKE SINGLE PUMP. 



The valve-gear of the Blake Single Pump is illustrated in 
Figs. I to 4 below. This is the arrangement of the boiler-feed 
and pressure pumps. The main valve, which controls the 
admission and exhaust of steam from the main cylinder, is car- 




COMBINED MOVABLE SEAT 
AND AUXILIARY VALVE 

^XHAUST 8109, 

H 




"EXHAUST V > 

PART SECTION OF AUXY. CYI^"""^ 




SECTIONAL VIEW 

OF 

STEAM END 



^^^^^^^s ^^^^^ 




118 THE SLIDE-VALVE AXD ITS ECXCTIOXS. 

ried by the chest -piston, and moves on the back of a movable 
seat. This movable seat is shown, bottom up, in Fig. 4. The 
passages A, B, C serve as steam-ports to the main cyHnder. 
The lugs G, G' control the admission of steam to the chest- 
cylinder, and the, holes H, H' control the exhaust from that 
cylinder. 

With the valve in the position shown, the course of the 
steam is through live-steam-passage N, through the port C to 
the right-hand end of the main cylinder, thus forcing the piston 
over to the left. Now, when the piston nearly reaches the left 
end of the cylinder the movable seat, by means described later, is 
shifced over to the left, so that the lug G covers the port E, 
while the lug G' moves off from the port E', thus admitting 
steam behind the chest-piston at the left-hand side. At the 
same time the hole H in the movable seat places K and S in 
communication, thus exhausting the steam from the right side 
of the chest-piston. This piston is then forced over to the 
right, and the port A is uncovered to live steam, ^^'hen the 
piston is near the right-hand end of its stroke all the operations 
are repeated in the opposite direction. 

There is one steam and one exhaust hole at each end of the 
chest-cylinder ; and the movable valve seat is, in effect, an aux- 
iliar}^ valve, which controls the admission and exhaust through 
said holes. The chest-piston passes over the exhaust-hole near 
the end of its stroke, and is thus cushioned on the imprisoned 
steam. The valve has no lap, a short travel, and opens simul- 
taneously for steam and exhaust. It remains open till the piston 
stroke is nearly completed, when it is suddenly moved to the 
other extremity of its travel. 

It will be seen that if means are provided to shift the mov- 
able seat, the rest of the operation is automatic. To accom- 
plish this the piston-rod is provided with a cross-head, on which 
is a pin, which engages a lever fulcrumed at P. A short link 
connects this lever with a tappet on a sleeve, which slides freely 



THE SLIDE-VALVE ON I' U MPS. 119 

on the valve-stem. Near the end of the stroke the tappet 
strikes one of the two collars on the stem and moves the valve- 
seat. By changing the position of these collars any desired 
amount of lead may be given to the valve. They should be set 
so as to admit steam in time to stop the piston before it strikes 
the cylinder head. If it is stopped too soon the steam required 
to fill the clearance space is wasted. 

DEAN BROTHERS. 

Dean Bros' Single-Pump is shown on page 120. The small' 
slide, shown in enlarged horizontal section in Fig. 6, controls 
the admission and exhaust of steam to and from the chest-piston. 
Sunk in the face of this slide are diagonal exhaust cavities d 
and d^ In the extreme positions of the slide these cavities 
connect one of the ports b, b^ with the exhaust port c, while the 
other port is left uncovered, as shown. The steam is admitted 
to one end of the chest-piston, and exhausted from the other 
end, forcing the piston over to one end of its cylinder ; and 
when the slide is moved to the other extremity of its travel 
this operation is reversed. The chest-piston carries the main 
slide-valve by means of a lug on its back ; and thus the main 
steam-ports are alternately opened to steam and exhaust, and 
with the stroke of the auxiliary slide properly regulated, steam 
Avill be admitted to the main cylinder in time to stop the piston 
at the end of each stroke. 

As will appear from the illustration, the auxiliary slide re- 
ceives its motion from a rocker, fulcrumed in the latitude of the 
valve-stem. It is a continuous motion ; and the ports leading 
to the chest-piston are therefore closed, except at the moment 
the main piston is being reversed. Hence there can be no 
<'blow through," or waste of steam, in case the chest -piston 
becomes worn. The stroke of the pump is regulated by length- 
ening or shortening the travel of the auxiliary slide, which is 
effected by shifting the stud in the slot in the upper end of the 
rocker. 



120 



THE SLIDE-VALVE AND IIS FUNCTIONS. 




do 06 







>' 



cf 



F' 



^es-3 






/^/ff-s 



3 



3-^ 



j^ 



Dean Bros' Valve Gear. 



/^^ 



THE SLIDE-VALVE O^V PUMPS. 121 



KNOWLES. 

In the Knowles Pump there is no auxiliary sHde-valve ; but 
when the main piston has almost completed its stroke the chest- 
piston is slightly rotated, whereby small ports in the underside 
of this piston -are put in communication with corresponding 
ports in the chest-cylinder, and thus steam is admitted to one 
end of this cylinder, and exhausted from the other end through 
small passages in the piston. The rest of the valve-motion is 
practically the same as that of the Blake pump, above described. 
The main piston-rod carries an arm which strikes a collar on the 
chest-piston rod, and moves the chest-piston if it should fail to 
start at the proper moment. 

THE DAVIDSON PUMP GEAR. 

The valve-gear consists of a valve, valve-pistons, valve-pin, 
and cam. The valve is actuated by a positive mechanical con- 
nection with the main piston-rod, and by the action of steam on 
valve-pistons. Fig. 79 shows the valve-gear and steam-cylinder 
in detail. The steam-chest consists of the cylinder M, valve A, 
and the pistons B and B' ; the pistons are connected, sufficient 
space being allowed between them for the valve A and the 
steam-ports f and i' . 

The valve is controlled and operated by the steel cam C 
acting on steel pin D, which passes through the valve into 
exhaust-port in which the cam is located. In addition to this 
mechanical operation steam is alternately admitted to and ex- 
hausted from the ends of the steam-chest by ports e and e^ 
operating the pistons B and B". 

Operation. — The pump being at rest with the valve A 
covering the main steam-ports f and f, the cam C holds the 
valve by means of valve-pin D, so that ports e and e' admit 
steam to one end of chest, and connect the other end with 
exhaust-port ; the steam acting on valve-pistons will move valve- 



122 



THE SLIDE-VALVE AND ITS FUXCTIOXS. 



pistons and valve, opening main ports f and i\ admitting steam 
to one end of steam-cylinder, and opening the other end to the 
exhaust. 

If the valve occupies any other position, the main ports f 
and f will be opened for the admission and exhaust of steam ; 
consequently it is evident that there is no, dead point, and that 
the pump will start from any point of stroke. 




Fig. 79. The Davidson Valve Gear. 

Steam being admitted to cylinder by one of the main ports, 
as f in illustration, the steam-piston, cam, valve, etc., will move 
in direction indicated by arrows. The first move of the cam 
will be to oscillate the valve preparatory to bringing it in proper 
position for the opening of the auxiliary steam-port e to live 



THE SLIDE-VALVE ON PUMPS. 



123 



steam, and e' to exhaust, and secondly to bring the valve to its 
closure (mechanically) slightly before the end of the stroke of 
main piston (thereby causing slight cut-off and compression), 
and fully opening auxiliary port e to steam and e' to exhaust. 
By the admission of steam to one end of the chest, the other 
being open to exhaust, the valve-pistons will move valve to such 
position as will allow the admission and exhaust of steam to and 
from cylinder for the return stroke. 

The main valve being as much under control of the piston- 
rod as is the valve of an ordinary steam-engine worked by an 
eccentric, secures a positive action, pump being capable of start- 
ing from any position and maintaining a uniform and full stroke. 

The steam-piston is absolutely prevented from striking the 
cylinder-heads by virtue of the mechanical valve-closure. 



THE CAMERON PUMP GEAR. 

Fig. 80 shows the valve-gear of the Cameron pump. There 
are two plain tappet-valves, one in each cylinder-head. Short 
valve-stems project into 
the cylinder ; and when 
the piston strikes one of 
these the valve is driven 
back and opens an 
exhaust-passage from 
the corresponding end 
of the chest-plunger, 
which immediately is 
shifted under the action 
of live steam on the 
opposite side of the 
plunger-head. There is 
a small hole in each end 
of the hollow plunger ; and when both tappet-valves are closed 
the steam, passing through these holes, leaves the plunger 




Fig. 80. The Cameron Pump Gear. 



12i THE SLIDE-VALVE AND ITS FUNCTIONS. 

entirely surrounded by live steam, and therefore in perfect 
balance endwise, until the piston strikes the tappet in the 
opposite cylinder-head, when the valve-moving operations are 
repeated in the opposite direction. The space back of the 
tappet-valve communicates with the steam-chest through a 
passage, shown in dotted lines ; and the valve is therefore 
closed by steam-pressure as soon as the piston moves back 
from the stem. It will be noticed that the piston closes the 
exhaust-passage before the end of the stroke. The confined 
steam forms a cushion between the piston and the cylinder- 
head, but a little passage is cut in the cylinder wall through 
which sufficient steam is admitted to start the piston on the 
return stroke. 

The main valve, carried by the chest-plunger, is shifted in 
the direction the piston travels at the end of the stroke, that is, 
in a direction opposite to that of a common slide-valve. This 
valve has, therefore, two cavities, each of which alternately puts 
the cylinder in communication with the steam-chest and the 
central exhaust-port. Steam is admitted under the outer valve- 
face, as shown in the cut. H is a lever, by means of which the 
steam-chest plunger may be reversed by hand when expedient. 

WORTHINGTON. 

Fig. 8 1 shows one side of a Duplex Pump built by Henry 
R. Worthington. 

Each individual pump actuates a rocker, which drives a valve 
.on the pump on the other side. That is, the rocker of one 
pump and the valve of the other pump are constantly in gear. 
Each valve is, therefore, moved independently of the piston in 
the same pump. The mutual operation is such that one pump 
must always be half a stroke, or more, behind the other. At 
the end of the stroke the valve covers both steam-ports ; but 
then the other pump is at mid-stroke, with its ports fully uncov- 



THE SLIDE-VALVE ON PUMPS. 



125 



ered, and thus the valve is always promptly carried over its dead 
center by the piston of the other pump. 

As one piston is about half a stroke ahead of the other, and 
the valve-motion should be the same on both pumps, it follows 
that one of the rockers must have a counter-arm above its ful- 
crum to move the valve in the proper direction. 

It will be noticed that the valve is confined between nuts on 
the valve-stem, and that they are not set closely against the 
valve; there is "lost motion." This lost 
motion is necessary, for otherwise the 
pump might not make full stroke. This 
is explained by the fact that the first 
part of the stroke is always made in less 



r^ 




Fig. 8i. The Worthington Duplex Pump. 



time than that of a corresponding part later in the stroke ; 
w^herefore the mid-point, in regard to time, or the middle of the 
stroke-period, comes later than half-stroke. The lost motion 
corrects this discrepancy when the valve-motion is reversed. 

A too tightly packed water piston or plunger may cause a 
pause at the commencement of the stroke, when the steam-ports 
are nearly covered, and consequently a later reversal of the valve- 
motion on the other side ; and from this cause the working of 



126 THE SLIDE-VALVE AND ITS FUNCTIONS. 

the pump may become somewhat irregular. The water-packing 
of a duplex pump should always be in good condition. 

All duplex pumps have separate exhaust-ports, as shown in 
the figure. The inner ports are only for exhaust, and the 
outer ones for live steam. After the exhaust-port has been 
opened, there remains exhaust-steam at atmospheric pressure in 
the cylinder and steam-passages ; this is expelled during the 
return stroke until the exhaust-opening is covered by the piston ; 
the remaining steam is then compressed, and forms a steam 
cushion between the piston and cylinder-head. One of the 
exhaust-ports is always covered by the valve. 

Steam cannot be used expansively in single-cylinder direct- 
acting pumps, because there is not enough kinetic energy stored 
in the water and moving parts to carry the piston to the end of 
its stroke ; but it may be used expansively in multi-cylinder 
pumps, for the pressure in each individual cylinder may not vary 
greatly in a compound system, when the admission is continuous 
during the entire stroke. The result is, of course, a considera- 
ble saving in steam. The speed of a pump is regulated by throt- 
tling the steam, and this has the disadvantage that during the 
dwell at the end of the stroke the steam-pressure in the cylinder 
is apt to rise ; that is, at a point where the increased pressure 
does no good. 

In a triple compound pump the work done in the high- 
pressure cylinder is only a small part of the whole work ; and it 
is, therefore, feasible to cut off the steam in this cylinder before 
the end of the stroke. 

Fig. 82 shows, in section, the high-pressure cyUnder of a 
** Triple Pump," built by Henry R. Worthington. It has three 
cylinders, connected in tandem, and it is on the Duplex plan ; 
each set of valves is driven by a rocker, which receives its mo- 
tion from the pump on the other side. The valves are all of the 
semi-rotary kind. They are, in fact, nothing but common D- 
valves on concave valve-seats. They are located under the cyl- 



THE SLIDE-VALVE ON PUMPS. 



12T 



inders for convenience, and it is a superior arrangement for drain- 
ing the cylinders, and the whole arrangement is eminently suita- 
ble for a simplified valve-gear. 

There are two steam-ports and two exhaust-ports in the 
steam-chest, arranged as the ports in an ordinary duplex pump ; 
but the steam and exhaust passages are united into one passage 
before entering the cylinder. In the steam-passage is a small 




Fig. 82. The Worthington Triple Gear. 

valve which cuts off the admission of steam before the end of 
the stroke. The point of cut-off is ordinarily fixed, but it can 
readily be changed by lengthening or shortening the rod con- 
nections ; that is, by giving the cut-off valves more or less lap. 

There are only two ports in the intermediate and low-pressure 
cylinders ; and the opening into the low-pressure cylinder is so 
located that the piston covers it before the end of the stroke, and 
is thus cushioned on the imprisoned steam. 



128 THE SLIDE-VALVE AND ITS FUNCTIONS, 



CHAPTER VI. 

ANGULARITY OF CONNECTING-ROD AND ECCENTRIC-ROD. 

THE ANGULAR MOTION OF THE CONNECTTNG-ROD. 

The motion of the crank-pin is both horizontal and vertical; 
that is, it may be dissolved in horizontal and vertical components, 
parallel with the center line of the engine and at right-angles to 
it ; and it was in the first chapter of this book assumed that the 
horizontal components, or the projections of the crank move- 
ments on the horizontal diameter of the crank-circle, represent 
exactly the movements of the piston in a horizontal engine, and 
no account was taken of the vertical, or up-and-down motion of 
the crank-pin. In other words, it was assumed that the horizon- 
tal distance from the crank-pin to the cross-head pin is the same 
at any point of the stroke, which is not true ; but the assump- 
tion is permissible, because it is sufificiently near the truth for a 
general investigation of the valve-action, and it greatly simplifies 
the construction of valve-diagrams. When the crank-pin is right 
on the center-line of the engine, its distance from the cross-head 
pin equals the length of the connecting-rod ; but when the crank- 
end of the connecting-rod is above or below the center-line, the 
horizontal distance between the pins is shortened more or less, 
according to the inclination of the rod. The piston is, therefore, 
always nearer the crank-end of the cylinder than has been as- 
sumed, except in its two terminal positions ; and in equal periods 
more steam is admitted during the head-end stroke, and less dur- 
ing the crank-end stroke. The piston moves faster in the head- 
end part of the cylinder and slower in the crank-end part ; and 
when the crank is in one of its *' quarter " positions, vertically 



ANGULARITY OF COXiVECTIiVG- AND ECCENTRIC-RODS. 129 

above or below the shaft, the piston has either passed its middle 
position in the cylinder or it has not yet reached it, according to 
which way it is moving. In constructing the valve-diagrams it 
was assumed that both crank and eccentric turned at a uniform 
rate, or moved through equal angles in equal time, which assump- 
tion is correct, and on this basis coincident positions of the pis- 
ton and valve were determined ; but, as no attention was paid to 
the angularity of the connecting-rod, some correction is neces- 
sary to present the piston-motion in its exact relation to the 
invariable time basis, and to suggest such changes of the valve 
and valve-motion as, will cause it to operate in closer harmony 
with the irregularities of the piston-motion. 

Hitherto one side of the piston only was considered, on the 
assumption that there was no difference in the piston-velocity 
from either cylinder-head, but now both sides of the piston will 
be considered conjunctively. A double-acting cylinder repre- 
sents two single-acting cylinders, as it were, and it appears that 
the piston-velocity is not the same in both of these. The main 
difficulty consists in equalizing the cut-offs on both sides of the 
piston when steam-admission and cut-off is regulated by a single- 
valve or conjugate-valves; and this is the condition assumed in 
the following. 

In a great number of engines a slight inequality of the 
■cut-offs is of no consequence, and no attention is paid to it, or 
it is partly corrected by the valve-setting. No power is gained 
by equalizing the cut-offs, and no steam is saved by it. The 
"most economical point of cut-off" is a vague conception, and 
the variation due to the angularity of the connecting-rod is not 
sufficient to have any practical bearing on this point ; but ine- 
quality of cut-off has unquestionably some disturbing effect on 
the speed of the engine, and this may be of some consequence 
in compound or high-expansion engines. 

The angularity of the eccentric-rod has a disturbing effect 
on the steam-lead which may become of some consequence in 



130 THE SLIDE-VALVE' AND ITS FUNCTIONS: 

shifting eccentric-engines, and Professor Sweet's method of 
obviating it will be explained. 

The circle in Fig. 83 represents the path of the crank-pin, 
and the direction of motion is shown by the arrow. The circle 
may also represent the time, or period of one revolution of the 
crank ; and as the rotative speed is supposed to be uniform, any 
part of the circle, measured in degrees or by its center angle, 
will represent a -proportionate period, or interval of time ; and 
the center-line of the crank, like the hand of the clock turning 
on its dial, will mark fractional parts of the period of revolu- 
tion, in strict conformity with its angular movements. 

While the crank is turning, the valve slides on the valve-face, 
and is supposed to open and close the ports at the proper 









>t 


2 


CUT-OFF 










'-^/ 


^^^y\^ ^^""^EXH. closure:. 






__,-- — ' 


f 


/\ 


/) 


\3 RELEASE 


_^-^ 


--"^ 




{/ 


/ 


y_ 


ijAOMIS. 








1 ' 

ADMIS'nI / 

release\K 




\/ 






Fig. 83 


EXH. CLOSUREX^ 


Jy^ 






Fig. 


83. 


6^ 


CUT-OFF 





moments for an equal steam distribution at both cylinder-ends,, 
or at both sides of the piston ; and the instant this occurs, or 
should occur, may be marked on the crank-circle, as shown. 

The diameter of the circle in Fig. 83 may represent the 
stroke of the piston toward the shaft from left to right and 
returning in the opposite direction ; and it may represent for- 
ward- and return-stroke for both cylinder-ends, or for both 
single-acting cylinders, as it were. Considering the head-end 
stroke, when the crank-pin is at point 2 the piston is at the 
middle of its stroke ; for if the connecting-rod be swung down 
from this point, without moving the cross-head, it will strike 
the center of the circle, as shown. Therefore, if steam is to be 
cut off exactly at half-stroke, it must occur when the crank is 



ANGULARITY OF CONNECTING- AND ECCENTRIC-RODS. 131 



in position 2, or the valve must close the port at the moment 
the crank arrives at point 2; and in that case arc 1-2, marks 
the admission-period. Considering the crank-end, the port 
should be closed when the crank-pin is at point 6 ; and in this 
case arc 5-6 represents the period of admission, which is longer 
than the period of admission at the head-end. The points of 
admission i and 5 are made diametrically opposite in order to 
get equal lead at both ends of the cylinder. 

Now the eccentric turns in unison with the crank; and if 
the points marked on the crank-circle be turned forward, 
through an angle equal to the angular advance of the eccentric, 




Fig. 84. 

they will be in their proper positions for the eccentric-circle. 
Thus Fig. 84 represents the eccentric-circle. V is the angle of 
advance, and the figures along the circumference mark the 
instants of opening and closing the ports, as in Fig. 83, but with 
the eccentric-radius as a pointer. 

If the valve-end of the eccentric-rod moves in a straight 
line which passes through the center of the shaft, the chords 
1-2 and 5-6 must be parallel, as shown in the first part of the 
book ; and which also will appear from a mere inspection of 
Figs. 84 and 85, if it be remembered that the valve-end of the 
rod must be at the same point when the valve opens and closes 



132 THE SLIDE-VALVE AND ITS FUNCTIONS. 

the port ; but, referring to Fig. 83, it will be observed that if 
points 2 and 6 are fixed, chords 1-2 and 5-6 cannot be parallel 
without changing the locations of points i and 5 in opposite 
directions. It is, therefore, not possible to equalize the cut-offc 
with the ordinary eccentric-rod motion without introduciLg 
unequal leads. 

Earlier cut-off can be obtained in the head-end stroke by in- 
creasing the head-end lap, and later cut-off may be obtained in 
the crank-end stroke by decreasing the crank-end lap. If the 
valve admits steam over the outside edges, both these changes 
may be made by lengthening the valve-rod ; and shortening it 
has the same effect, if steam is admitted over the inside port- 
edges, or if the valve is moved by a counter-arm on the rocker ; 
but, in any event, such change involves less lead at the head-end 
and more at the crank-end. If the valve has ample lead, a little 
change either way will not be of much consequence ; but if there 
is little or no lead or negative lead, unequal steam-laps are mor^e 
objectionable; and, as the port-opening equals half the travel, 
minus the lap, the opening for early cut-offs may become unduly 
restricted at one end of the cylinder. This, however, may under 
certain conditions be partly avoided by using a short eccentric- 
rod, as will presently be explained. 

THE ANGULAR MOTION OF THE ECCENTRIC-ROD. 

The up-and-down motion of an eccentric of a horizontal en- 
gine draws the eccentric-rod towards the shaft, as shown in Fig. 
85, where the rod is represented disproportionally short for the 
sake of clearness. To correct this, the immediate valve connec- 
tions must be lengthened if the valve moves in the same direc- 
tion relative to the crank-shaft as does the eccentric-rod pin, and 
shortened if the motion is reversed by a counter-arm. In other 
words, the head- and crank-end laps are made unequal. 

The angular vibration of the eccentric-rod gives a quicker 
motion to the valve at one end of its travel and a slower motion 



ANGULARITY OF CONNECTING- AND ECCENTRIC-RODS. 133 



at the other end ; and the period of admission is, therefore, 
under certain conditions, shortened at the head-end and length- 
ened at the crank-end without changing the laps. The result is 
more equal cut-offs with equal port-openings ; but if the admis- 
sion periods must be diametrically opposite, the inequality of 
these periods must necessarily make the leads unequal. 

In order to obtain results as here stated, the steam must 
either be admitted over the inside port-edges, or else the valve 
must be moved by a counter-arm rocker ; otherwise the inequal- 
ity of laps and port-openings will be increased instead of di- 
minished. 




Fig. 85. 

The length of the eccentric-rod, compared with the throw of 
the eccentric, is generally too great to make the influence of its 
angular vibration of much consequence ; but if the facts here 
mentioned are fully understood, they may occasionally be used 
to advantage by a discriminating designer. 

If the valve-end of the eccentric-rod is guided by a common 
rocker-arm, it may become sUghtly elevated at the middle of its 
travel, which has a quite inappreciable effect in the direction of 
later release and compression if the engine is '^ running over," 
and a depression towards the end of its travel has the opposite 
effect on the lead and cut-off, but the effect in either case is 
practically nil. 



134 THE SLIDE-VALVE -AND ITS FUNCTIONS. 



STEAM- AND EXHAUST-LAPS.. 

As the diameter of the crank-circle, Fig. 83, represents the 
forward stroke and the return-stroke for both ends of the cyhn- 
der, points of cut-off, release, and exhaust-closure may be located 
on this diameter at equal distances from the ends ; and by strik- 
ing arcs with radius equal to the length of the connecting-rod, 
as shown, the corresponding crank-positions are located. 

Points I, 2 and 3, 4 mark admission and cut-off, release, and 
exhaust-closure positions of the crank-pin for the head-side of the 
piston, and 5, 6 and 7, 8 mark corresponding positions for the 
crank-side. Ordinarily all the chords connecting each pair of 
these points must be parallel, and to suit this requirement, the 
points must be rearranged, according to the best judgment of 
the designer. 

The distances from the center of the circle to the chords, 
measured by the proper scale, give the required laps ; and it will 
be noticed that release and compression may be very nearly 
equalized for both cylinder-ends by suitably proportioned ex- 
haust-laps. The exhaust-lap for the crank-end becomes larger 
than that for the head-end, and the only objection to this is the 
reduction of port-opening at the crank-end. If the exhaust-laps 
are made equal, it is impossible, with the ordinary valve-gear, to 
make the compression curves on the indicator card equal without 
greatly disturbing the lead and cut-off. 

EQUALIZING BOTH LEAD AND CUT-OFF. 

If the cut-offs are to be equal on both sides of the piston 
without changing the leads the periods of admission cannot be 
diametrically opposite. Any period may be changed either way 
by turning the eccentric on the shaft ; but in that event all the 
periods will be changed conjunctively. Instead of turning the 
eccentric on the shaft, the eccentric-rod may be turned ; for the 
eccentric-action is in the direction of the rod ; and if the rod is 



ANGULARITY OF CONNECTING- AND ECCENTRIC-RODS. 135 

turned in a different direction, the points marking opening and 
closing of the ports will be turned the same amount in the same 
direction on both the eccentric and crank-circle ; and if the valve- 
end of the rod receives a reciprocating angular motion relative 
to the crank-shaft, there will be a corresponding angular dis- 
placement of the conjugate points,* according to the instantane- 
ous angular displacement of the rod ; and, therefore, by suitably 
guiding the end of the eccentric-rod, the admission-periods can 
bs properly timed for equal leads and equal cut-offs on both sides 
of the piston. 

The mean direction of the eccentric-rod for any period of 
open or closed port is represented by a straight line passing 
through the center of the corresponding arc on the eccentric 
circle and at right angles to the chord. If the valve-end of the 
eccentric-rod be guided by an inclined rocker-arm, as shown in 
Fig. 84, the mean direction of the rod for the admission 
period i~2 will be different from its mean direction for the 
admission-period 5-6, as indicated in the figure ; it being under- 
stood that when the eccentric is at either point i or 2, the 
pin is at point 1 2, and when the eccentric is at 5 or 6 the pin is 
at point 56 — these being the coincident positions of the eccen- 
tric-rod pin when the steam-edges of valve and port come to- 
gether at the head- and crank-end respectively. 

Now, if by variation of the mean inclination of the rod for 
points 12 and 56 respectively, the angle of variation equals the 
angle of convergence of the admission-chords, 1-2 and 5-6, in 
Fig. 83, the cut-off may be fixed at exactly half the stroke 
either way by giving the valve proper laps, and without disturb- 
ing the leads. The laps are determined by the distance from 
the center of the rocker-arm arc to points 12 and 56 respec- 
tively ; and the port-openings are determined by the distance of 
these points from the ends of the arc. 

If the points on the eccentric-circle are correctly spaced, 

♦Points I, 2 and 3, 4, etc., are for obvious reasons called conjugate points. 



136 THE SLIDE-VALVE AND ITS FUNCTIONS. 

points 12 and 56 may be located by striking arcs with a radiub 
equal to the length of the eccentric-rod from the corresponding 
points on the circle ; and for the equalization of lead and cut-off, 
the end of the rod may be guided in any manner whatever if it 
passes through points 12 and 56; but the rocker-arm affords 
the only satisfactory means of accomplishing this. The rocker- 
fulcrum may be located above the eccentric-rod ; but this would 
make the port-openings unequal, as shown in Fig. 84, while in 
the other position the port-openings may be equalized by using 
a rocker-arm of the proper length. The exhaust-periods will be 
advanced a trifle on account of the upward curvature of the 
rocker-arc ; that is, they will come a trifle later in the stroke, 
which may be an advantage rather than otherwise. The curva- 
ture of the arc has practically no effect on the equalization of 
release and compression, which depends on the correct propor- 
tioning of the exhaust-laps. 



THE INCLINED ROCKER FOR SHIFTING-ECCENTRIC ENGINES. 

When the inclined rocker is applied to variable cut-off 
engines it cannot equalize the cut-offs at all points of the stroke ; 
for the equalization depends on the angle between the two mean 
directions of the eccentric-rod for the head-end and crank-end 
admission-periods, as shown in Fig. 84. As the laps of the 
valve are unchangeable, the distance between points 12 and 56 
is practically constant for all cut-offs ; and the rocker-arm can, 
therefore, only equalize the cut-offs for two or four points on 
the crank-circle, which give the proper convergency or mutual 
inclination of the admission-chords. This convergency is gi'eat- 
est for the mid-stroke cut-off, and it decreases by earlier and 
later cut-offs, and becomes practically nil at the beginning of 
the stroke. If, for example, the rocker-fulcrum be so located as 
to equahze the cut-offs at one-fourth of the stroke, the earlier 
cut-offs will be too early at the head-end and too late at the 



ANGULARITY OF CONNECTING- AND ECCENTRIC-RODS. 137 

crank-end ; and an ordinary rocker-arm will give very nearly 
equal cut-offs near the beginning of the stroke. 

EQUALIZING THE LEAD IN SHIFTING-ECCENTRIC ENGINES. 

The angular vibration of the eccentric-rod draws the valve 
towards one end of the steam-chest, and this can be provided 
for by making one lap a little longer than the other ; but if the 
throw of the eccentric varies, as when it is shifted across the 
shaft, the lead cannot be equalized in this manner for more than 
one proportion of cut-off, but nearly equal leads at both cylinder- 
ends may be obtained for the whole range of cut-off by means 
of the inclined rocker, as will now be explained. 




Fig. 86. 

If steam is admitted over the inside port-edges, the eccen- 
tric must be located on the crank-side of the shaft ; and in that 
case Fig. 86 represents the eccentric-circle, and the rocker will, 
in its middle position, be leaning toward the cylinder-end, as 
shown. Let the center of the eccentric be at B and A at the 
commencement of the head-end stroke and the crank-end stroke 
respectively, and let the annexed short curves represent the 
path of the center of the eccentric, when it is moved across 
the shaft ; then if the corresponding positions of the eccentric- 
rod pins are at D and C respectively, and if lines from these 
points to the middle points of curves B and A are parallel, it 
will be seen that if the rod is swuns: from the outer to the 



138 



THE SLIDE-VALVE AND ITS FUNCTIONS. 



inner end of the curved path in either position, points D and C 
will be shifted very nearly the same amount, in opposite direc- 
tions, and thus nearly equal lead may be obtained for both ends 
of the cylinder, irrespective of the points of cut-off.* It should 
be observed that the valve-end of the eccentric-rod must be 
angularly advanced, relative to the crank-shaft while moving 
toward the shaft ; and in order that, under this condition, the 
cut-offs may be equalized for some intermediate points in the 
stroke, it is necessary that the admission-period for the head-end 
be on the rocker-side of the eccentric. The valve must, there- 




Fig. 87. 
fore, either admit steam over the inside edges, or else the 
motion from the eccentric must be reversed by means of a 
counter-arm on the rocker. By such arrangement the cut-offs 
may become more equal than with the ordinary rocker ; but if 
the crank-end admission-period is on the rocker-side of the 
shaft the inequality of the cut-olEfs will be greater than when a 
common rocker is used. Also note that equal port-openings 
cannot be had unless the rocker-fulcrum is behind the rocker- 
arm, in the direction of rotation of the eccentric ; that is, if we 
imagine the rocker swung around the shaft. 

In the Straight-Line engine steam is admitted over outside 

* Professor Sweet explained this to the writer in 1882 by drawing seven chalk-lines on a 
blackboard. 



ANGULARITY OF CONNECTING- AND ECCENTRIC-RODS. 139 

port-edges, and the form of the rocker used on some of these 
engines is indicated in Fig. ^j.^ 

UNEQUAL LAPS FOR A VARIABLE CUT-OFF ENGINE. 

It is questionable whether any attempt should be made to 
equalize the cut-offs in shifting-eccentric engines by varying the 
laps without the inclined rocker ; for any considerable dissimi- 
larity of the laps will have a decidedly bad effect on the early 
cut-offs and early leads, on account of the short travel and 
small port-opening ; but the release and compression may be 
equalized for both sides of the piston, to a great extent, by 
making the head-end exhaust-lap smaller and the crank-end lap 
longer. In the early cut-offs, the valve opens and closes for the 
exhaust nearer the middle of the piston-stroke, and the greater 
angularity of the connecting-rod at these points neutralizes, to 
some extent, the effect of reduced travel as far as the unequal 
laps are concerned ; and as the smallest exhaust-opening is 
never much less than the amount of steam-lap, the conditions 
are altogether favorable for an equalization of the exhaust- 
action by means of the exhaust-laps. 

The graphical methods used or suggested in connection with 
the subject-matter of this chapter are useful in a wider sense, 
as illustrative of a simple and rational method for the exact de- 
termination of the steam distribution in the cylinder, the lapse 
of the valve, and the port-openings a method which is generally 
applicable, and which involves few artifices and no curve-tracing, 
and therefore should commend itself to the practical designer. 

* The inclined rocker was discussed by Mr. F. A. Halsey in tht American 3Iac/ii?ust for 
February 28 and March 14, 1889, 



INDEX, 



[Illustrations are indicated by an asterisk (*).] 



PAGE 

Admission 9, lo 

Period of, 5*, 8, 9, 10, 11, 12*, 15, 16, 21, 
13J, 135. 138 

Point of 9, II, 12* 

Allen, John F 75 

Allen Locomotive Valve, the 35* 

Allfree Valve Gear, the 57, 58* 

Angle of Advance, 5*, 10, 11, 12*, 14*, 15, 16, 21 

Angularity of Connecting-rod, 11, 128, 129, 130* 

Of Eccentric-rod . . . .6, 129, 132, 133* 



Ball, Frank H 

Telescopic Valve, tlie 

Balanced Area 43* 

Balancing a Common T)-va!ve . 42, 43*, 44 

Balance, the Thomas 

Balanced Valve wiili Independent Cut- 
off 

Begtrup's Eccentric 97 

P)lake Single Pump, the 

Buckeye Flat Valve, the 

Round Valve, the 

Valve dear, the 102, 

Vibrating Cut-off . . . . 1 11, 112*, 



,99* 
1 17* 
103* 
106* 
104* 
113* 



Cameron Pump-gear, the 123* 

•Clark, D. K 27 

Clearance, 27, 28, 35, 52, 53*, 54, 63*, 64*, 80, 

III* 
Combination Valve, Limitations of the, 16, 17 
Compound Rocker, the Buckeye .... 70* 

Valves . . . 50. 51*. 52, 53*, 54, 55. 56* 

Compression 11, 12*, 17, 27 

Condenser, Effect of 27, 43 

Connecting-rod, Angularity of, ii, 128, 129, 130* 

Cooling Surface 34, 33i 76 

Corliss, George 31 

Corliss Gear, Limitations of ... . 65, 66 

Setting of the 72 

•Corliss Valves 1,62*, 63* 

Dimensions of 71 

Motion of 62*, 63*, 64, 65 



PAGE 

Creeping Steam 43 

Cut-off 10, II, 12*, 16, 17 

Eccentric Journal on Engine Shaft, 90, 91 , 92 

Equalized 132 

(lonzen bach, the 81* 

Independent 80 

Meyer's 85* 

Point of 5*, II, 12*, i6 

Range of 25 

Single Valve 23 

Square 22,31 

Unequality of 129 

^'aried by Rotating Eccentric, 90*, 93*, 96* 

Cut-cff Valves, 80, 81*, 85*, 90*, 93*, 9^)*, loi*, 
103*, ic6*, 109*, no*, 112*, 113* 

On Back of Main Valve 83 

On an Anchor Plate 83 

On a Stationary Valve Seat .... 81 

Simple Form of 81,82* 

With Constant Travel on Main Valve, 

99, lOT*, 103*, 106*, 112* 
Worked by Means of a Rocking Link, 

106, 107* 

Cylinder, Double Acting -4, 229 

Single Acting 4, 50*, 153* 

Dash-pot Action 65,66 

Dead Center 9, n 

Setting Engine on 32 

Davidson's Pump Gear 121, 122* 

Dean Brothers' Single Pump Gear . iig, 120* 
Double Ported Valves . . 34*, 39*, 41*, 63* 

Duplex Pump 125* 

D-valve i, 2*, 4, 7, 8, 18, 41, 96 

Diagram 12* 

Cylindrical 78*, 127* 

Limitations of the 16,17 

On Pumps, the 115 

Double-Acting Engine 4,8 

Eccentric 5,9, n 

Eccentricity of 6 



141 



142 



INDEX. 



PAGE 

Eccentric, At Half -Throw 7 

Exhaust 8, 70 

Begtrup's 97,^* 

Radius of 6 

Rod, Angularity of . . .6,129,132,133* 

Single 17 

Shiftable 16, 21 

Steam 8, 69 

Throw of e>, 16 

Rotative on Shaft. . 83,90, 103, 112, 113 

Exhaust Cavity 2*, 8, 17, 20, 41 

Eccentric 8, 70 

Clearance 4 

Closure 12, 17 

Edge 17 

Lap 2*, 3, 7, 8, 9, 17 

Negative 3,5^* 

Lead 10, 12 

Line 19 

Opening 8, 16, 38 

Passage 18 

Period 5*, 8, 9, 12*, 15, 16 

Port 3, 7, 8, 62*, 63* 

Valve 7,21,37,111* 

Face of Valve 2 

Free Expansion 31 

Four-valve Systems 61 

Friction of Steam 19 

Gonzenbach Cut-off, the 81* 

Valve Diagram of 83* 

Governor, Shaft, 37, 50, 53, 92, 93, 99, 109, 

no, 112 
Vertical 107 

Gridiron Valves with Independent Cut-off, 96 

Gridiron Valves . 75, 76*, 96* 109*, 112,* 113* 

Halsey, F. A 139 

Hill, Edward K 76 

Hill Valves, the 76* 

Ideal Engine, Valves of the ... 47*, 48* 

Independent Cut-off 80 

On Four-valve Engines 108 

Improved Slide-valves 34 

Inclined Rocker for Shifting- Eccentric, 

,36, 137*, 138* 
Indicator Diagram, Theoretical . . . 14,* 24 

Inside Lap 3 

Intervening Steam Pressure 44 

Knowles' Pump-gear 121 

Lap 2*, 5*, 7, 9, 1 1, 15, 16 

On Separate Exhaust ^'a'.ve .... 23 



PACK 

Lap, Travel and Port-Opening ... 24, 25 

Steam and Exhaust 134 

Unequal 133, ,34, ,35^ 13^ 

Lapless Valves n 

Leakage Loss 32 

Lead 10, 12*, 16, 21* 

Angle 26 

Negative 10, 27 

Notes About 25 

Variable 21*, 26, 29*, 31 

Limitations of the Combination Valve . . 16 

Of the Corliss Gear 65,66 

Links 29*, 72, 107* 

Locomotive Valves, Motion of . . . 28, 29* 
Low Receiver Pressure 43 

McEwen Valve, The 39* 

Mcintosh & Seymour Valves, The . 108, log* 

Meyer Cut-Off, The 85* 

Limitations of 89 

Multiporting 31 

Negative Lap on Cut-Off Valves, 82*, 86*, 87, 

gj*, 100*, loi*, 104* 

Negative Exhaust-Lap 3, 56* 

Lead 10, 27 

Outside-Lap 3 

Oscillating Valves ... i 

Piston-Valves 1,46*, 47* 

With Independent Cut-Off . . 105,106* 

Piston Velocity 22, 25* 

Period of Revolution 9 

Of Steam Distribution 11 

Port 2*, 18, 19*, 20 

Area of 19 

Contraction of 18, 19,* 43* 

Formula for 19 

Port-Opening . . . 7, 9, 15, 17, 19,* 22, 23, 25* 

Equality of 138 

Initial 10 

Variation of 24, 25* 

Porter Allen Engine. Valves of the ... 72* 

Pressure Relieving Device . . . 42, 43*, 45* 

Plate 36*, 38, 73*, 74 

Exhaust 38 

Pumps, Slide-Valve on 115 

Blake, the 117* 

Cameron, the 123* 

Davidson, the 121,122* 

Dean Brothers' 119. 120* 

Knowles' 121 

Worthington, the 124, 125* 

Triple Compound 126, 127* 



JXDEX. 



14a 



PAGE 

Receiver Press are, Kigh 51 

Low 43 

Relation Between Lap and Travel . . 15, 21* 

Release. Point of 12, 23, 24 

Early 24 

And Compression, Constant, 21*, 23, 38, 

57, So 

Relieved Area ...'.. 43 

Reversal of Crank Motion 15 

Revolution, Period of 9, 16 

Rice & Sargent, Valves Designed by . . 64* 
Richardson Balanced Valye, the .... 44 

Rider, A. K 90 

Cut-Off , the 89, 90 

Rocker, Compound 103, 104* 

Counter- Arm 30, »33, 138* 

Inclined 135, 136, 137*, 138* 

Robinson, S. W 43 

Russell Engine, Valves of the . . . 110*, iii* 

Semi-Rotary Valves . i, 62*, 63*, 64*, 78* 
Single-Valve Gear, Allfree, the ... 57, 58* 

Single-Acting Cylinders 4, 50*, 53* 

Slide-Valve, the Common 1,2* 

Cylindrical .... i, 62*, 63*, 64*, 78* 

Simplest Form of 4, 5*, 8 

Spring-Rings 47,48, 106* 

Steam, Creeping 43,45 

Admission 7 

Friction of 19 

Dry, Wet, or Superheated 19 

Eccentric 8 

Lap 2*, 3, 7, II, 1 2» 

Lead 10 

Line 19, 31 

Port 2*, 3, 18 

Passages J 8, 32 

Ports, Supplementary, 17, 32, 35*, 36*, 46* 
And Exhaust Edges, Transposition of, 38 

Velocity of ig 

Valve 7 

Straight Line Balanced Valve, the . . . 36* 

Variations of 38, 39* 

Sweet, John E 15, 130, 138 

Sweet's Valve Diagram .... 14*, 15, 21* 

Telescopic Valve 41* 

Thomas, W. J 44 

Thomas Balance, the 44, 45* 

Thomson, J. W ic2 



PAGE 

Throw of Eccentric 6, 12*, 16 

Travel and Lap 21*, 22 

of Valve 9, 12*, 15, 17 

Unequal Laps for Variable Cut-Off Engines , 

139 

Valve Dimensions 20 

Face of 2 

Seat of 2 

Motion in Relation to Piston Motion . 9 

Without Lap 11 

Diagrams, Primitive 12* 

Sweet's 14*, 21* 

For Corliss Engines . . . 67*, 70* 

Simple Cut-Otl" 82* 

For the Gonzenbach Cut-Off . . 83* 

For Meyer's Cut-Off 86* 

For Rotative Adjustment, 91*, 92*, 94* 

For Link Connection 107* 

Combined Steam and Exhaust . . 16* 17* 

For High-Speed Engines, 16, 35*, 365*39*, 

4x*, 43*, 45*, 46*, 47*, 48*, 50*, 51*, 53*, 

56*, 58* 

Flat Balanced 36*, 39*, 73* 

Leakage of . 32 

Separate for Steam and Exhaust, 21,61, 63*, 
73*, 76* 

Unbalanced 17 

Cut-Off 80 

Expansion 80 

Gridiron .... 75, 76*, 96*, 109*, 113* 
Of the Straight-Line Type .... 37, 39* 

Compound 50, 51*, 53, 56* 

Designed by Messrs. Rice & Sargent, 63, 64* 

Variable Valve Travel 15 

Vauclain Valve, the 54, 56* 

Velocity of Steam 19 

Piston 25* 

Westinghouse Standard Valve, The, 49, 50* 

Compound Valve, the 53* 

Wheelock Valves, the 78*, 79 

Wiredrawing 31, 37 

Worthington, Henry R 116 

Duplex Pump, the 124,125* 

Triple-Pump Gear, the 127* 

Zeuner, Dr 88 



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chine and Boiler Construction, in two parts. Part I., General En- 
gineering Data. Part II., Boiler Construction. With 51 Plates ano 
numerous illustrations specially drawn for this work. Folio, half mor. 
London, 1895. $25.00 

Horner. Plating and Boiler Making. A Practical Handbook for Work- 
shop Operation, including an Appendix of tables by A Foreman Pattern 
Maker. 338 illustrations. i2mo. London, 1895. ^3.00 



LIST OF BOOKS. 

Button. Steam Boiler Construction: A Practical Handbook for Engi- 
neers, Boiler Makers, and Steam Users, With upwards of 300 illustra- 
tions. 3d edition. 8vo. London, 1898. $6.00 

Munro. Steam Boilers : Their Defects, Management, and Construction. 
3d edition enlarged, with numerous illustrations and tables. i2mo. 
London, 1889. ^1.50 

Roper. The Steam Boiler: Its Care and Management. With instruc- 
tions for increasing the Efficiency and Economy, and insuring the Dura- 
bility and Longevity of all classes of Steam Boilers, Stationary, Loco- 
motive, Marine, and Portable. With Hints and Suggestions and Advice 
to Engineers, Firemen, and Owners of Steam Boilers. 4th edition, 
revised. i2mo, tuck, mor. Philadelphia, 1897. ^2.00 

Use and Abuse of the Steam Boiler. Illustrated. 12th edition. 

i2mo, mor. tucks. Philadelphia, 1897. $2.00 

Rose. Steam Boilers. A Practical Treatise on Boiler Construction and 
Examination. For the Use of Practical Boiler Makers, Boiler USers, 
and Inspectors, and embracing in plain figures all the calculations neces- 
sary in designing and classifying Steam Boilers. 73 engravings. 8vo. 
Philadelphia, 1897. $2.50 

Rowan. On Boiler Incrustation and Corrosion. New edition, revised 
and enlarged by F. E. Idell. i6mo, boards. New York, 1895. $0.50 

Sexton. Pocket Book for Boiler Makers and Steam Users, comprising a 
variety of useful information for Employer and Workman, Government 
Inspectors, Board of Trade Surveyors, Engineers in charge of Works 
and Slips, Foremen of Manufactories, and the General Steam-Using 
Public. 4th edition, revised and enlarged. 32mo, roan. London, 1895. 

$2.00 

Stromeyer. Marine Boiler Management and Construction. Being a 
Treatise on Boiler Troubles and Repairs, Corrosions, Fuels, and Heat. 
On the Properties of Iron and Steel, on Boiler Mechanics, Workshop 
Practices, and Boiler Designs. 2d edition, Bvo. London, 1901. $4.00 

Thurston. Manual of Steam Boilers: Their Designs, Construction, 
and Operation. For Technical Schools and Engineers. 183 engrav- 
ings in text. 7th edition. 8vo. New York, 1901. $5.00 

A Handbook of Engine and Boiler Trials, and of the Indicator 

and Prony Brake, for Engineers and Technical Schools. 4th edition, 
revised. Illustrated. 8vo, New York, 1897. $5.00 

Watson, E. P. Small Engines and Boilers. A Manual of Concise 
and Specific Directions for the Construction of Small Steam Engines 
and Boilers of Modern Types from five Horse-power down to model 
sizes. i2mo, cloth. Illustrated. $1.25 



D. VAN NOSTRAND COMPANY. 

Traill. Boilers : Their Construction and Strength. A Handbook of 
Rules, Formulae, Tables, etc., relative to Material, Scantlings, and Pres- 
sures, Safety Valves, Springs, Fittings and Mountings, etc. For use of 
Engineers, Surveyors, Draughtsmen, Boiler Makers, and Steam Users. 
With illustrations. 3d edition, i2mo, mor. London, 1896. $5.00 

Triplex. Marine Boilers. A Treatise on the Causes and Prevention of 
their Priming, with Remarks on their General Management. Illustrated. 
i2mo. Sunderland, 1899, . $2.00 

Watson. Small Engines and Boilers. A Manual of Concise and 
Specific Directions for the Construction of Small Steam Engines and 
Boilers of Modern Types from five horse-power down to model sizes. 
i2mo, cloth. Illustrated with numerous diagrams and half-tone cuts. 
New York, 1899. $1.25 

The intention of the author in writing this work has been to fur- 
nish specific directions and correct dimensioned plans for small 
engines and boilers. 

Wilson. A Treatise on Steam Boilers : Their Strength, Construction, 
and Economical Working. Enlarged and illustrated from the Fifth Eng- 
lish edition by J. T. Flather. i2mo. New York, 1897. $2.50 

Boiler and Factory Chimneys: Their Draught Power and Stability. 

4th edition, i2mo. London, 1899. $1.50 

FUELS. 

Abbott. Treatise on Fuel. Founded on the original Treatise of Sir 
W. Siemens. Illustrated. i6mo. New York, 1891. $0.50 

Barr. A Catechism on the Combustion of Coal and the Prevention 
of Smoke : a Practical Treatise for Engineers, Firemen, and others 
interested in Fuel Economy, and the Suppression of Smoke from 
Stationary Steam Boiler Furnaces, and from Locomotives. i2mo, 
cloth. Illustrated. New York, 1900. $1.50 

Clark and Williams. Fuel : Its Combustion and Economy, consisting of 
Abridgments of Treatise on the Combustion of Coal and the Econorhy 
of Fuel. With extensive additions in recent practice in the Combustion 
and Economy of Fuel, Coal, Coke, Wood, Peat, Petroleum, etc. 4th 
edition. i2mo. London, 1891. $1.50 

Hodgetts. Liquid Fuel for Mechanical and Industrial Purposes. Illus- 
trated. 8vo. London, 1890. $2.50 

Phillips. Fuels : Solid, Liquid, and Gaseous ; their Analysis and Valua- 
tion. For the use of Chemists and Engineers, i2mo. London, 1896. 

;^o.8o 



LIST OF BOOKS. 

Sexton, A. H. Fuels and Refractory Materials. 8vo. Cloth. London, 
1897. $2.00 

Williams. Fuel : Its Combustion and Economy. Consisting of an 
Abridgment of " A Treatise on the Combustion of Coal and the Pre- 
vention of Smoke." With extensive additions by D. Kinnear Clark. 
4th edition. London, 1891. |i.5o 

GAS ENGINES. 

Clerk. The Theory of the Gas Engine. 2d edition, with Additional 
Matter edited by F. E. Idell. i6mo. New York, 1891. $0.50 

The Gas Engine. History and Practical Working. With 100 illus- 
trations. 8th edition, revised. i2mo. New York, 1899. $4.00 

Donkin. A Text-Book on Gas, Oil, and Air Engines : or Internal Com- 
bustion Motors without Boiler. 154 illustrations. 3d edition, re- 
vised and largely rewritten. 8vo. London, 1900. $7.00 

Goodeve. On Gas Engines : with Appendix describing a Recent Engine 
with Tube Igniter. i2mo. London, 1887. $1.00 

Hiscox, Gardner D. Gas, Gasoline and Oil Vapor Engines. Their 
Theory and Power. 3d edition, revised and enlarged. 8vo. cloth. 
Illustrated. New York, 1900. $2.50 

Lockert, Louis. Petroleum Motor-Cars. i2mo, cloth. $1.50 

HEAT.— THERMODYNAMICS. 

Anderson. On the Conversion of Heat into Work. A Practical Hand- 
book on Heat Engines. 4th edition. Illustrated. i2mo. London, 
1901. $2.25 

Box. Treatise on Heat as Applied to the Useful Arts, for the use of 
Engineers, Architects, etc. 8th edition, i2mo. London, 1895. $5.00 

McCulloch. Elementary Treatise on the Mechanical Theory of Heat and 
its application to Air and Steam Engine. 8vo. New York, 1876. $3.50 

Maxwell. Theory of Heat. New edition, with Corrections and Addi- 
tions by Lord Rayleigh, Sec. R. S. Illustrated. 12 mo. New York, 
1897. $1.50 

Peabody. Thermodynamics of the Steam Engine and other Heat En- 
gines. 4th edition, 8vo. New York, 1901. $5.00 

Rontgen. The Principles of Thermodynamics. With special Applica- 
tions to Hot Air, Gas, and Steam Engines. With additions from Profes- 
sors Verdet, Zeuner, and Pernolet. Translated, newly and thoroughly 
revised and enlarged by Professor A. Jay Du Bois. 732 pages. 3d edi- 
tion. 8vo. New York, 1896. ^5.00 



D. VAN XOSTRAND COMPANY. 

Tyndall. Heat considered as a mode of Motion. 6th edition. i2mo. 

New York, 1890. ^2.50 

Williams. On Heat and Steam : embracing New Views of Evaporization, 

Condensation, and Expansion. Illus. 8vo. Philadelphia, 1882. $2.50 

HOISTING MACHINERY. 

Colyer. Hydraulic, Steam and Hand Power-Lifting and Pressing Ma- 
chinery. 72 large plates. 8vo. London, 1892, $10.00 

Glynn. Treatise on the Construction of Cranes and other Hoisting Ma- 
chinery. 7th edition. Illustrated. London, 1887. ^0.60 

Marks. Notes on the Construction of Cranes and Lifting Machinery. 
i2mo. London, 1899. New and enlarged edition. net, 1.50 

Towne. A Treatise on Cranes, descriptive particularly of those designed 
and built by the Yale and Towne Manufacturing Company, owning and 
operating the Western Crane Company , including also a description of 
light hoisting machinery as built by the same makers. 8vo. New York, 
1883. ^i.oo 

Weisbach and Hermann. The Mechanics of Hoisting Machinery, in- 
cluding Accumulators, Excavators, and Pile-drivers. A Text-book for 
Technical Schools and a guide for Practical Engineers. Authorized trans- 
lation from the second German edition by Karl P. Dahlstrom. 177 illus- 
trations. 8vo. New York, 1893. $375 

ICE-MAKING MACHINES. 

Dixon. Manual of Ice-Making and Refrigerating Machines. A Treatise 
on the Theory and Practice of Cold-Production by Mechanical Means. 
i6mo. St Louis, 1894. $1.00 

Leask. Refrigerating Machinery. Its Principles and Management. 

With numerous illustrations. 2d edition, revised. 8vo. London, 

looi. §2.00 

Ledoux. Ice-Making Machines: the Theory of the Action of the 
Various Forms of Cold-producing or so-called Ice-Machines. Trans- 
lated from the French. 248 pages and numerous Tables. i6mo. 
New York, 1897. $0.50 

Redwood. Theoretical and Practical Ammonia Refrigeration. A Prac- 
tical Handbook for the use of those in charge of Refrigerating Plants. 
Illustrated with numerous Tables. i2mo. New York, 1896. $1.00 

Wallis-Tayler. Refrigeration and Cold Storage ; being a complete 
Practical Treatise on the Art and Science of Refrigeration. 8vo, 
cloth. Illustrated. net, $4.50 



LIST OF BOOKS. 



INDICATORS. 

Bacon, Treatise on the Richards Steam Engine Indicator. With a 
Supplement, describing the latest Improvements in the Instruments for 
Taking, Measuring, and Computing Diagrams. Also an Appendix, con- 
taining Useful Formulas and Rules for Engineers. 23 diagrams. 4th 
edition. i6mo, flex. New York, 1883. $1.00 

Ellison. Practical Applications of the Indicator. With reference to the 
Adjustment of Valve Gear on all Styles of Engines. 2d edition. 8vo. 
100 engravings. Chicago, 1897. $2.00 

Hemenway. Indicator Practice and Steam Engine Economy. With 
Plain Directions for Attaching the Indicator, Taking Diagrams, Comput- 
ing the Horse-Power, Drawing the Theoretical Curve, Calculating Steam 
Consumption, Determining Economy, Locating Derangement of Valves, 
and making all desired deductions ; also. Tables required in making the 
necessary computations, and an Outline of Current Practice in Testing 
Steam Engines and Boilers. 6th edition. i2mo. New York, 1899. 

^2.00 

Le Van. The Steam Engine Indicator and its Use. A Guide to Practi- 
cal Working Engineers for greater economy, and the better Working of 
Steam Engines. i8mo, boards. New York, 1900. $0.50 

— — The Steam Engine and the Indicator : Their Origin and Progressive 
Development, including the most recent examples of Steam and Gas 
Motors, together with the Indicator, its Principles, its Utility, and its Ap- 
phcation. Illustrated by 205 engravings, chiefly of Indicator-cards. 8vo. 
Philadelphia, 1890. ^4.00 

Porter. A Treatise on the Richards Steam Engine Indicator, and the 
Development and Application of Force in the Steam Engine. 5th edi- 
tion, revised and enlarged. 8vo. London, 1894. ^^3.00 

Pray. Twenty Years with the Indicator. Being a Practical Text-book 
for the Engineer or the Student, with no Complex Formulae. With 
many illustrations and rules as to the best way to run any Steam Engine 
to get the most economical results. How to Adjust Valves and Valve 
Motions Correctly. Full directions for working out Horse-Power, the 
Amount of Steam or Water per Horse-Power, Economy and Fuel. Ex- 
tended directions for Attaching the Indicator, what Motions to use and 
those not to use. Full directions for Computation of Power by Planim- 
eter and other methods, with many tables and hints. 8vo. New York, 
1896. I2.50 



D. VAN- NOSTRAND COMPANY. 



INJECTORS. 

Kneass. Practice and Theory of the Injector. 8vo. New York, 1898. 

$1.50 
Nissenson. Practical Treatise on Injectors as Feeders of Steam Boilers. 

Illustrated. 8vo, paper. New York, 1890. $0.50 

Pochet. Steam Injectors ; Their Theory and Use. i6mo, boards. New 

York, 1890. $0.50 

INSTRUCTIONS TO ENGINEERS, FIREMEN, 
AND BOILER ATTENDANTS. 

Bale. A Hand-Book for Steam Users, being Rules for Engine Drivers 
and Boiler Attendants, with Notes on Steam Engine and Boiler Manage- 
ment and Steam Boiler Explosions. i2mo. London, 1890. $0.80 

Edwards. 900 Examination Questions and Answers for Engineers and 
Firemen (Stationary and Marine), who desire to obtain a U. S. Govern- 
ment or State License. A new, revised, and enlarged edition. 32mo, 
mor. Philadelphia, 1901. ^1.50 

Grimshaw. Steam Engine Catechism. A Series of Direct Practical 
Answers to Direct Practical Questions. Mainly intended for Young En- 
gineers. i8mo. New York, 1897. $2.00 

Grimshaw. The Engine Runner's Catechism. Telling how to Erect, 
Adjust, and Run the principal Steam Engines in use in the United States. 
Illustrated. i8mo. New York, 1898. $2.00 

Hawkins. Maxims and Instructions for the Boiler Room. Useful to 
Engineers, Firemen, and Mechanics, relating to Steam Generators, Pumps, 
Appliances, Steam Heating, Practical Plumbing, etc. 184 illustrations. 
8vo. New York, 1901. $2.00 

Aids to Engineers' Ezaminations. Prepared for Applicants of all 

Grades with Questions a.id Answers. A Summary of the Principles and 
Practice of Steam Engineering. i2mo, leather, gilt edge. New York, 
1901. $2.00 

Reynolds. The Engineman's Pocket Companion and Practical Educator 
for Engineman, Boiler Attendants, and Mechanics. Illustrated. i6mo, 
4th edition. London, iqoo. $1.40 

Roper. Instructions and Suggestions for Engineers and Finemen who 
wish to Procure a License, Certificate, or Permit to take charge of any 
class of Steam Engines or Boilers, Stationary, Locomotive, and Marine. 
i8mo, mor. Philadelphia, 1894. $2.00 



LIST OF BOOKS. 

Rose. Key to Engines and Engine-running. A Practical Treatise 
upon the Management of Steam Engines and Boilers for the use of 
those who desire to pass an examination to take charge of an engine 
or boiler. i2mo, cloth. New York, 1899. $2,50 

Questions and Answers for Engineers. This little book contains all 

the questions that Engineers will be asked when undergoing an exami- 
nation for the purpose of procuring licenses, and they are so plain that 
any Engineer or Fireman of ordinary intelligence may commit them to 
memory in a short time. 6th edition. i8mo, mor. Philadelphia. $2.00 

Stephenson. Illustrated Practical Test Examination and Ready Refer- 
ence Book for Stationary, Locomotive, and Marine Engineers, Firemen, 
Electricians, and Machinists, to procure Steam Engineer's license. i6mo, 
Chicago, 1892. $1.00 

Stromberg. Steam User's Guide and Instructor. Plain and Correct Ex- 
planations in regard to Engines, Pumps, Dynamos, and Electricity. Prac- 
tically, so that Engineers, Machinists, Firemen, and Electricians of Lim- 
ited Education can understand and become expert practical engineers. 
i6mo. St. Louis, 15th edition. 1900. $2.50 

Watson. How to Run Engines and Boilers. Practical Instruction for 
Young Engineers and Steam Users. 2d edition. Illustrated. i6mo. 
New York, 1896. $1.00 

Zwicker. Practical Instructor in questions and answers for Machinists, 
Firemen, Electricians, and Steam Engineers. 24mo. St. Louis, Mo., 
1898. $0.75 

LOCOMOTIVE ENGINEERING. 

Grimshaw. Locomotive Catechism. Containing nearly 1,300 Questions 
and Answers Concerning Designing and Constructing, Repairing and 
Running Various Kinds of Locomotive Engines. Intended as Exami- 
nation Questions and to Post and Remind the Engine Runner, Fireman, 
or Learner. 176 illustrations. i2mo. New York, 1898. $2.00 

Hill. Progressive Examinations of Locomotive Engineers and Firemen. 
r6mo. Terre Haute, Ind., 1899. $0.50 

Meyer. Modern Locomotive Construction. 1,030 illustrations. 4to. New 
York, 1899. $10.00 

Phelan. Air Brake Practice, being a description of the construction, ob- 
jects sought, and results obtained, by the Westinghouse automatic air 
brake, as well as complete directions for operating it under the many 
diverse condhions in daily practice. 3 large folding plates. i2mo. New 
York.' 4th edition. ^i.oo 



D. VAN NOSTRAND COMPANY. 

Reagan. Locomotive Mechanism and Engineering. i2mo, with 145 il- 
lustrations. New York, 1898. $2.00 

Reynolds. Locomotive Engine Driving. A Practical Manual for Engi- 
neers in charge of Locomotive Engines. 8th edition, enlarged. i2mo. 
London, 1892. ^1.40 

The Model Locomotive Engineer, Fireman, and Engine Boy : Com- 
prising a Historical Notice of the Pioneer Locomotive Engines and their 
Inventors. i2mo. London, 1895. ^r.8o 

Continuous Railway Brakes. A Practical Treatise on the several 

Systems in use in the United Kingdom ; their Construction and Perform- 
ance. Numerous illustrations and tables. 8vo. London, 1882. $3.60 

Engine Driving Life : Stirring Adventures and Incidents in the Lives 

of Locomotive Engine Drivers. 2d edition, with additional chapters. 
i2mo. London, 1894. $0.80 

Rogers. Pocket Primer or Air Brake Instruction. Stiff paper cover. ^0.50 

Roper. Hand-Book of the Locomotive; including the construction of 
engines and boilers and running of locomotives. 15th edition, revised. 
i2mo, mor. tucks. Philadelphia, 1897. $2.50 

Sinclair. Locomotive-Engine Running and Management. A Practical 
Treatise on Locomotive Engines, showing their performance in running 
different kinds of trains with economy and Despatch. Also, directions 
regarding the care, management, and repairs of Locomotives and all their 
connections. Illustrated by numerous engravings. 21st edition, revised. 
i2mo. New York, 1901. $2.00 

Stretton. The Locomotive Engine and its Development. A Popular 
Treatise on the Gradual Improvements made in Railway Engines be- 
tween the years 1803 and 1892. Illustrated. i2mo. 5th edition. Lon- 
don, 1896. $1.50 

Synnestvedt. Diseases of the Air Brake System. Their Causes, Symp- 
toms, and Cure. Illustrated. i2mo. 1894. $1.00 

Woods. Compound Locomotives. 2d edition, revised and enlarged by 
D. L. Barnes. 8vo. Illustrated. Chicago, 1894. $3.00 



MACHINE TOOLS AND APPLIANCES. 

Harrison. The Mechanic's Tool Book, with Practical Rules and Sugges- 
tions for Machinists, Iron Workers, and others. i2mo. New York, 
1882. $1.50 



LIST OF BOOKS. 

Hasluck. The Mechanics' Work-shop Handy Book. A Practical Man- 
ual on Mechanical Manipulation. Embracing Information on Various 
Handicraf - Processes, with Useful Notes and Miscellaneous Memoranda. 
i2mo. London, 1895. ^0.50 

Knight. Mechanician. A Treatise on the Construction and Manipulation 
of Tools, for the Use and Instruction of Young Engineers and Scientific 
Amateurs. 4th edition. 4to. London, 1888. $7—5 

Lukin. Young Mechanic. Containing directions for the use of all kinds 
of Tools and for construction of Steam Engines and Mechanical Models, 
including the Art of Turning in Wood and Metal. Illustrated. i2mo. 
New York. $1.75 

Rose. Complete Practical Machinist. Embracing Lathe Work, Vise 
Work, Drills and Drilhng, Taps and Dies, Hardening and Tempering, 
the Making and Use of Tools, Tool Grinding, Marking out Work, etc. 
Illustrated by 356 engravings. 19th edition, greatly enlarged. i2mo. 
Philadelphia, 1901. $2.50 

Shelley. Work-shop Appliances. Including descriptions of some of the 
Gauging and Measuring Instruments, Hand Cutting Tools, Lathes, Drill- 
ing, Planing, and other Machine Tools used by Engineers. loth edition, 
with an additional chapter on Milling, by R. R. Lister. Illustrated. 
i2mo. London, 1S97. $1.50 

Smith. Cutting Tools worked by Hand and Machine. 14 plates and 51 
illustrations. 2d edition. i2mo. London, 1884. $i-5o 

Usher. Modern Machinist. A Practical Treatise on Modern Machine 
Shop Methods, describing in a comprehensive manner the most Approved 
Methods, Processes, and Appliances Employed in Present Practice, etc. 
257 illustrations. i2mo. New York, 1895. $2.50 

Watson. Modern Practice of American Machinists and Engineers. i2mo. 
Illustrated. Philadelphia, 1897. $2.50 

MECHANICAL DRAWING AND MACHINE 
DESIGN. 

Andre. Draughtsman's Hand-Book of Plan and Map Drawing; including 
Instructions for the preparation of Engineering, Architectural and Me- 
chanical Drawings, with numerous illustrations, and colored examples. 
8vo. London, 1891. $3-75 

Appleton's Cyclopaedia of Technical Drawing. Embracing the Principles 
of construction as appHed to Practical Design. With numerous illustra- 
tions of Topographical, Mechanical, Engineering, Architectural, Perspec- 
tive, and Free-hand Drawing. 8vo, leather. New York, 1896. $9,00 



D. VAN NOSTRAND COMPANY 

Barber. Engineers' Sketch Book of Mechanical Movements, Devices, 
Appliances, Contrivances, Details employed in the Design and Con- 
struction of Machinery for every Purpose. Collected from numer- 
ous sources and from actual work. Classified and arranged for 
reference. Nearly 2000 Illustrations. 4th edition. 8vo. London, 
igo2. $4.00 

Building and Machine Draughtsman. A Practical Guide to the Pro- 
jection and Delineation of Subjects met with in the practice of the 
engineer, machinist, and building constructor, etc.; by practical 
draughtsmen. i2mo. London, 1891. $2.00 

Burns. Illustrated Architectural Engineering and Mechanical Draw- 
ing Book. For the use of Schools, Students, and Artisans. loth 
edition, revised and corrected, with additional sections on impor- 
tant departments of the art. 8vo. 284 illustrations. New York, 
1893. $1,00 

Cathcart, Prof. Wm. L. Machine Design: Fastenings, with Tables, 
Diagrams and Engravings. 8vo, cloth. Illustrated. In Press. 

Davidson. Drawing for Machinists and Engineers. Comprising a com- 
plete course of Drawing adapted to the requirements of Millwrights and 
Engineers ; also, course of practical instruction in the coloring of me- 
chanical drawings. 4th edition. i6mo. London. $1.75 

Donaldson. Drawing and Rough Sketching for Marine Engineers, with 
Proportions, Instructions, Explanations, and Examples ; also How to De- 
sign Engines, Boilers, Propellers, Paddle Wheels, Shafts, Rods, Valves, 
etc. 6th edition. Illustrated. London, 1899. $300 

Faunce. Mechanical Drawing, prepared for the use of the students of 
the Mass. Institute of Technology. 2d edition, revised and enlarged. 
Illustrated and 8 plates. i2mo. Boston, 1900. $1.25 

Fox, Wm., and C. W. Thomas, M. E. A Practical Course in Mechan- 
ical Drawing. 2d edition, revised. i2mo, cloth, with .plates. $1.25 

Halliday. First Course in Mechanical Drawing (Tracing). Folio, 
paper. London, 1889. $0.75 

Mechanical Graphics. A Second Course in Mechanical Draw- 
ing, with Preface by Professor Perry. 8vo. London, 1889. $2.00 

Hulme. Mathematical Drawing Instruments and How to Use Them. 
4th edition. i2mo. New York, 1890. $1.50 

Klein. Elements of Machine Design. Notes and Plates, 8vo. Beth- 
lehem, Pa., 1892. $6.00 



LIST OF BOOKS. 

Low and Bevis. Manual of Machine Drawing and Design. 3d edition, 
753 illustrations. 8vo. London, igoi $2.50 

MacCord. Practical Hints for Draughtsmen. Illustrated with 68 dia- 
grams and full page plates. 3d edition, 4to. New York, 1890. $2.50 

Kinematics, or Practical Mechanics. A Treatise on the Transmis- 
sion and Modification of Motion and the Construction of Mechanical 
Movements. For the use of Draughtsmen, Machinists, and Students of 
Mechanical Engineering, in which the laws governing the motions and 
various parts of Mechanics, as affected by their forms and modes of con- 
nection, are deduced by simple geometrical reasoning, and their applica- 
tion is illustrated by accurately constructed diagrams of the different 
mechanical combinations discussed. 4th edition. 8vo. New York. 
1899. $5.00 

Minifie. Mechanical Drawing. A Text-Book of Geometrical Drawing, 
for the use of Mechanics and Schools, in which the Definitions and Rulef 
of Geometry are familiarly explained : the Practical Problems are ar. 
ranged from the most simple to the more complex, and in their descrip. 
tion technicalities are avoided as much as possible. With illustrations 
for Drawing Plans, Sections, and Elevations of Buildings and Machin- 
ery; an Introduction to Isometrical Drawing, and an Essay on Linear 
Perspective and Shadows. Illustrated by over 200 diagrams, engraved 
on steel. With an Appendix on the Theory and Application of Colors. 
8vo. New York, 1893. ^4.00 

Geometrical Drawing. Abridged from the octavo edition, for the 

use of Schools. Illustrated with 48 steel plates. 9th edition. Revised 
and enlarged. i2mo. New York, 1890. ^2.00 

Palmer. Mechanical Drawing, Projection Drawing, Geometric and Oblique 
Drawing, Working Drawings. A Condensed Text for Class Room use. 
Svo. Columbus, O. 1894. ^i.ot 

^einhardt, Chas. W. Lettering for Draftsmen, Engineers and Students. 

A Practical System of Free-hand Lettering for Working Drawings, 
nth thousand. Oblong, boards. $1.00 

The Technic of Mechanical Drafting. A Practical Guide to 

neat, correct and legible Drawing, containing many Illustrations, 
Diagrams and full-page Plates. 4to, cloth. Illustrated. $1.00 



D. VAN NOSTRAND COMPANY. 

Ripper. Machine Drawing and Design for Technical Schools and Engi- 
neer Students. Being a complete course of Instruction in Engineering 
Drawing, with Notes and Exercises on the Application of Principles to 
Engine and Machine Design, and on the Preparation of Finished Col- 
ored Drawings. Illustrated by 52 plates and numerous explanatory 
drawings. 8vo. London, 1897. ^6.00 

Roberts. Drawing and Designing for Marine Engineers. 21 large fold- 
ing plates and many other illustrations throughout the text. Svo. Lon- 
don, 1898. fo.oo 

Rose. Mechanical Drawing Self-Taught. Comprising Instructions in 
the Selection and Preparation of Drawing Instruments, Elementary In- 
struction in Practical Mechanical Drawing, together with Examples in 
Simple Geometry and Elementary Mechanism, including Screw Threads, 
Gear Wheels, Mechanical Motions, Engines and Boilers. Illustrated by 
330 engravings. 4th edition, revised. Svo. Philadelphia, 1902. $4.00 

Shaw. Mechanical Integrators. Including the various Forms of Pla- 
nimeters. i8mo, boards. Illustrated. New York, 1886. $0.50 

Smith. Graphics, or the Art of Calculation by Drawing Lines, applied 
especially to Mechanical Engineering. Part I. Text, with Separate Atlas 
of Plates — Arithmetic, Algebra, Trigonometry, Vector and Lecor Addi- 
tion, Machine Kinematics, and Statics of Flat and Solid Structures. Svo. 
London, 1888. $5.00 

Stanley. Descriptive Treatise on Mathematical Drawing Instruments, 

their Construction, Uses, Qualities, Selection, Preservation, and Sugges- 
tions for Improvements, with Hints upon Drawing and Coloring. 5th 
edition. i2mo. London, 1878. ^2.00 

Tomkins. Principles of Machine Construction ; being an application of 
Geometrical Drawing for the Representation of Machinery. Text i2mo. 
Plates 4to. New York. $3- 50 

Unwin. Elements of Machine Design. Part I. General Principles, Fas- 
tenings, and Transmissive Machinery. i6th edition. i2mo. London, 
1898. ^2.00 

Part II. Chiefly on Engine Details. i2mo. 13th edition, revised 

and enlarged. London, 1901. ^1.50 

Warren. Elements of Machine Construction and Drawing : or, Machine 
Drawing, with some elements of descriptive and rational kinematics. 
2 vols. Text and plates. Svo. New York, ^7.50 



LIST OF BOOKS, 

MECHANICAL ENGINEERS' HAND-BOOKS. 

Adams. Hand-Book for Mechanical Engineers. 2d edition. Revised 
and enlarged. i2mo. London, 1897. $2.50 

Appleton's Cyclopaedia of Applied Mechanics : a Dictionary of Mechani- 
cal Engineering and the Mechanical Arts. Edited by Park Benjamin. 
Nearly 7,000 illustrations. Revised and improved edition. 2 vols. 8vo, 
leather. New York, 1896. ^15.00 

Bale. Steam and Machinery Management : A Guide to the Arrangement 
and Economical Management of Machinery, with Hints on Construction 
and Selection. Illustrated. 2d edition. i2mo. London, 1890. (Weale's 
Series.) ^i.oo 

Benjamin. Wrinkles and Recipes. Compiled from the Scientific Ameri- 
can. A collection of Practical Suggestions, Processes, and Directions, 
for the Mechanic, Engineer, Farmer, and Housekeeper. With a Color 
Tempering Scale and numerous Wood Engravings. 5th edition. 
i2mo. New York, 1901. $2.00 

Byrne. Hand-Book for the Artisan, Mechanic, and Engineer. Compris 
ing the Grinding and Sharpening of Cut^-ing Tools, Abrasive Processes, 
Lapidary Work, Gem and Glass Engraving, Varnishing and Lackering 
Apparatus, Materials and Processes for Grinding and Polishing, etc. 8vo. 
Illustrated. Philadelphia, 1887. ,$5.00 

Carpenter. Text-Book of Experimental Engineering. For Engineers and 
for Students in Engineering Laboratories. 249 illustrations. 5th revised 
edition. 8vo. New York, 1898. ^6.00 

Chordal. Extracts from Chordal's Letters. Comprising the choicest 
selections from the Series of Articles which have been appearing for the 
past two years in the columns of the American Machinist. With over 50 
illustrations, i2mo. 9th edition. New York, igoi. $2.00 

Clark. Manual of Rules, Tables and Data for Mechanical Engineers, 
based on the most recent investigations. With numerous Diagrams. 
7th edition. 1,012 pages. London, 1897. $5.00 

Half morocco. $7.50 

• Mechanical Engineers' Pocket-Book of Tables, Formulae, Rules, 

and Data. A Handy-Book of Reference for Daily Use in Engineer- 
ing Practice. i6mo, mor. 4th edition. London, 1899. $3.00 

Dixon. The Machinists' and Steam Engineers' Practical Calculator. 
A Compilation of useful Rules and Problems, arithmetically solved, 
together with general information applicable to Shop Tools, Mill 
Gearing, Pulleys and Shafts, Steam Boilers and Engines. Embracing 
valuable Tables and Instructions in Screw Cutting, Valve and Link 
Motion. 3d edition. i6mo, mor., pocket form. New York, 1901. $1.25 



D. VAN NOSTRA ND COMPANY. 

Engineering Estimates, Costs, and Accounts. A Guide to Commercial: 
Engineering. With numerous Examples of Estimates and Costs of Mill- 
wright Work, Miscellaneous Productions, Steam Engines and Steam 
Boilers, and a Section on the Preparation of Costs Accounts. By a Gen- 
eral Manager, 2d edition. 8vo. London, 1896. $4.80 

General Machinist, Being a Practical Introduction to the Leading Depart- 
ments of Mechanism and Machinery, the Communication of Motion or 
the Transmission of Force by Belt, Rope, Wire Rope, and Pulley Gearing 
— Toothed-Wheel and Frictional Gearing ; together with the details of 
the component and essential parts of mechanism — Shafts, Pedestals, 
Hanger, Clutches, etc., and of the methods of fitting up Machines, Screw 
Bolts, Riveting, etc. By various practical writers and machinists. 75 
illustrations and 4 folding plates. 8vo. London, 1891. ^2.oa 

Grimshaw. Hints to Power Users. Plain, Practical Pointers, free from 
high Science, and intended for the man who pays the bills. i2mo. New 
York, 1 89 1. ^i.oa 

Hasluck. Mechanic's Workshop Handy-Book. A Practical Manual on 
Mechanical Manipulation. Embracing Information on Various Handi- 
craft Processes, with Useful Notes, and Miscellaneous Memoranda. 
i2mo. London, 1888. $0.50 

HasweU. Engineers' and Mechanics' Pocket Book, Containing Weights 
and Measures, Rules of Arithmetic, Weights and Materials, Latitude and 
Longitude, Cables and Anchors, Specific Gravities, Squares, Cubes, and 
Roots, ,etc. ; Mensuration of Surfaces and Solids, Trigonometry, Me- 
chanics, Friction, Aerostatics, Hydraulics and Hydrodynamics, Dynamics, 
Gravitation, Animal Strength, Windmills, Strength of Materials, Limes, 
Mortars, Cements, etc. ; Wheels, Heat, W^ater, Gunnery, Sewers, Com- 
bustion, Steam and the Steam Engine, Construction of Vessels, Miscel- 
laneous Illustrations, Dimensions of Steamers, Mills, etc.; Orthography 
of Technical Words and Terms, etc. 67th edition. Revised and 
enlarged. i2mo, mor. tuck. New York, 1902. $4.00 

Hawkins. Hand-Book of Calculations, for Engineers and Firemen ; 
relating to the Steam Engine, the Steam Boiler, Pumps, Shafting, 
etc. Illustrated. 8vo. New York, 1902. $2.00 

Button. Works Manager's Hand-Book of Modern Rules, Tables, and 
Data for Civil and Mechanical Engineers, Millwrights, and Boiler Makers, 
Tool Makers, Machinists, and Metal Workers, Iroti and Brass Founders, 
etc. 5th edition, revised, with additions. 8vo, half-bound. London, 
1895- ^6.00 



LIST OF BOOKS. 

Hutton. Practical Engineer's Hand-Book. Comprising a Treatise on 
Modern Engines and Boilers, Marine, Locomotive, and Stationary, and 
containing a large Collection of Rules and Practical Data Relating to 
Recent Practice in Designing and Constructing all kinds of Engines, 
Boilers, and other Engineering Work. 5th edition, carefully revised, with 
additions. 370 illustrations. 8vo. London, 1896. $7-0O' 

Kent. Mechanical Engineers' Pocket-Book. A Reference Book of Rules, 
Tables, Data, and Formulae, for the Use of Engineers, Mechanics, and 
Students. 1,087 pages. 5th edition. i2mo. New York, 1902. $5.00 

Knight. American Mechanical Dictionary. A Descriptive Word Book 
of Tools, Instruments, Chemical and Mechanical 'Processes; Civil, Me- 
chanical, Railroad, Hydraulic, and Military Engineering. A History of 
Inventions. General Technological Vocabulary, and Digest of Mechani- 
cal Appliances in Science and the Industrial and Fine Arts. 3 vols. 
Illustrated, 8vo. Boston, 1884. ^24.00 

Supplement to the above, $9.00 

The 4 vols., complete, ^27.50 

Lockwood's Dictionary of Terms used in the Practice of Mechanical En- 
gineering. Embracing those current in the Drawing Office, Pattern Shop, 
Foundry, Fitting, Turning, Smiths' and Boiler Shops, etc., comprising 
upwards of 6,000 definitions. Edited by a Foreman Pattern Maker. 
3d edition. i2mo. London, 1902, $3.00 

Molesworth. Pocket-Book of Useful Formulae and Memoranda for 
Civil and Mechanical Engineers. 24th edition, revised and enlarged. 
Pocket-book form. London, 1901. $2.00 

Moore. Universal Assistant and Complete Mechanic : Containing over 
One Million Industrial Facts, Calculations, Receipts, Processes, 
Trade Secrets, Rules, Business Forms, Legal Items, etc. Illustrated. 
i2mo. New York. $2.50 

Rankine. Useful Rules and Tables relating to Mensuration, Engineering 
Structures, and Machines. 7th edition, thoroughly revised by W. J. 
Millar. With Electrical Engineering Tables, Tests, and Formulas for the 
use of Engineers, by Prof. A. Jamieson. i2mo. London, 1889. ^4.00 

Roper. Engineers' Handy-Book. Containing a full explanation of the 
Steam Engine Indicator, and the Use and Advantage to Engineers and 
Steam Users. With Formulas for estimating the Power of all Classes 



D. VAN NOSTRAND COMPANY. 

at Steam Engines ; also Facts, Figures, Questions, and Tables, for Engi- 
neers who wish to qualify themselves for the United States Navy, the 
Revenue Service, the Mercantile Marine, or to take charge of the better 
class of stationary Steam Engines. Illustrated. 15th edition. 
i6mo, mor. tucks. Philadelphia, 1901. $3-50 

Scribner. Engineers' and Mechanics' Companion. Comprising United 
States Weights and Measures, Mensuration of Superfices and Solids; 
Tables of Squares and Cubes ; Square and Cube Roots ; Circumference 
and Areas of Circles ; the Mechanical Powers ; Centres of Gravity ; Gravi- 
tation of Bodies; Pendulums; Specific Gravity of Bodies; Strength, 
Weight, and Crush of Materials ; Water-wheels, Hydrostatics, Hydraulics, 
Statics, Centres of Percussion and Gyration ; Friction Heat ; Tables of 
the Weight of Metals, Scantling, etc.; Steam and Steam Engine. 
2ist edition, revised. i6mo, full mor. New York, 1902. $1.50 

Spons' Tables and Memoranda for Engineers, and convenient refer- 
ence for the pocket. 12th edition. 64mo, roan, gilt edges. London, 
1901. In cloth case. $0.50 

Mechanics' Own Book. A Manual for Handicraftsmen and 

Amateurs. Complete in one large vol., 8vo, containing 700 pages 
and 1,420 Illustrations. 6th edition. London, igoi. $2.50 

Dictionary of Engineering. Civil, Mechanical, Military, and Naval, 



with Technical Terms in French, German, Italian, and Spanish. 8 vols. 
8vo, cl. London, 1874. Each, $5.00 
Supplement to above. 3 vols., cl. London, 1881. Each, $5.00 



Templeton. Practical Mechanics' Workshop Companion. Completing 
a great variety of the most useful Rules and Formulas in Mechanical 
Science, with numerous Tables of Practical Data and Calculated Results 
for Facilitating Mechanical Operations. i8th edition, revised, mod- 
ernized, and considerably enlarged, by Walter S. Hutton. i6mo, 
leather. London, 1902. $2.00 

Engineers', Millwrights', and Mechanics* Pocket Companion. 

Comprising Decimal Arithmetic, Tables of Square and Cube Roots, Prac- 
tical Geometry, Mensuration, Strength of Materials, Mechanical Powers, 
Water Wheels, Pumps and Pumping Engines, Steam Engines, Tables of 
Specific Gravity, etc. Revised, corrected, and enlarged from the 8th Eng- 
lish edition, and adapted to American Practice, with the addition of much 
new matter. Illustrated by J. W. Adams. i2mo, mor. tucks. New York, 
1893. ^2.00 



LIST OF BOOKS, 

Van Cleve. English and American Mechanic. An every-day Hand-Book 
for the Workshop and the Factory. Containing Several Thousand Re- 
ceipts, Rules, and Tables indispensable to the Mechanic, the Artisan, and 
the Manufacturer. A new, revised, enlarged, and improved edition. 
Edited by Emory Edwards, M.E. i2mo. Philadelphia, 1893. $2.00 

MECHANICS (ELEMENTARY AND APPLIED). 

Church. Notes and Examples in Mechanics ; with an Appendix on the 

Graphical Statics of Mechanism. 128 illustrations and 6 plates. 8vo. 

2d edition, New York, 1900. $2.00 

Cotterill. Applied Mechanics, an Elementary General Introduction to 

the Theory of Structures and Machines. Illustrated. 3d edition. 8vo. 

London, 1895. ^5.00 

and Slade. Lessons in Applied Mechanics. i2mo. London, 1894. 

Net ^1.25 

Dana. A Text-Book of Elementary Mechanics for the use of Colleges 

and Schools. 12th edition. i2mo. New York, 1901. $i-50- 

DuBois. Elementary Principles of Mechanics. Designed as a Text-Book 

for technical schools. 3 vols. 8vo. New York. 

Vol. I. Kinematics. l3'5o 

Vol. II. Statics. 1^4.00 

Vol. III. Kinetics. $3-5o 

Garnett. Treatise on Elementary Dynamics. For the use of Colleges 

and Schools. 5th edition. 8vo. London, 1889. Net$\.y:t 

Geldard. Statics and Dynamics. Illus. i2mo. London, 1893. $1.50 

Goodeve. Principles of Mechanics. New edition, rewritten and enlarged. 

i2mo. London, 1889. $2.50= 

Manual of Mechanics. An Elementary Text-Book for Students of 

Applied Mechanics. Illustrated. i2mo. London, 1881. $o.8a 

Hancock. Text-Book of Mechanics and Hydrostatics. With over 500- 
diagrams. 8vo. New York, 1894. $i-75 

Hughes. Condensed Mechanics : a selection of Formulae, Rules, Tables, 
and Data for the Use of Engineering Students, Science Classes, etc., in 
accordance with the requirements of the Science and Art Department. 
i2mo. London, 1891. ^1-°° 

Jamieson. Elementary Manual of Applied Mechanics. Specially ar- 
ranged for the use of First Year Science and Art, City and Guilds of 
London Institute, and other Elementary Engineering Students. 
4th edition, revised and enlarged. i2mo. London, 1900. $1.25. 



Z>. FAA^ NOSTRAND COMPANY, 

Kennedy. Mechanics of Machinery. With numerous illustrations. i2mo. 
London, 1886. ^3.50 

Kinematics of Machinery; or, The Elements of Mechanism. i6mo, 

boards. New York, 1881. $0.50 

Nystrom. New Treatise on Elements of Mechanics. 8vo. Philadelphia, 
1875. ^2.00 

Perry. Applied Mechanics. Illustrated. i2mo. London, 1901. 

$2.50 

Practical Mechanics. Being the Fourth Volume of " Amateur Work Il- 
lustrated." Plates and illustrations. 4to. London. ^3.00 

Rankine. Applied Mechanics, comprising Principles of Statics, Cinemat- 
ics, and Dynamics, and Theory of Structures, Mechanism, and Machines. 
i2mo. i6th edition, thoroughly revised, by W. J. Millard, Lon- 
don, 1901. $5-oo 

and Bamber. Mechanical Text-Book ; or, Introduction to the 

Study of Mechanics and Engineering. With numerous Diagrams. 
4th edition, revised. 8vo. London, 1890. $3- 50 

Stahl and Woods. Elementary Mechanism. A Text-Book for Stu- 
dents of Mechanical Engineering, nth edition, revised and en- 
larged. Illustrated. i2mo. New York", 1901. $2,00 

Weisbach. Theoretical Mechanics, with an Introduction to the Cal-. 
cuius. Translated from the 4th German edition by E. B. Coxe. 
9th edition, revised. 8vo, cloth. New York, 1899. $6.00 

Sheep. $7.00 

Vol. II., Part I. Hydraulics and Hydraulic Motors. $5-00 

Vol. IL, Part 2. Heat, Steam, and Steam Engines. ^5.00 

Vol. III., Part I. Kinematics and Machinery of Transmission. $5.00 
Vol. III., Part 2. Machinery of Transmission and Governors. $5.00 

Wood. Elements of Analytical Mechanics. With numerous examples 
and illustrations. For use in Scientific Schools and Colleges. 7th edi- 
tion, revised and enlarged, comprising Mechanics of Solids and Mechanics 
of Fluids, of which Mechanics of Thirds is entirely new. 8vo. New 
York, 1900. $3-oo 

Principles of Elementary Mechanics. Fully illustrated. 9th edition. 

i2mo. New York, 1894. ^i—S 

Wright. Text-Book of Mechanics. With numerous examples. 3d edi 
tion. i2mo. New York. ^2.50 



LIST OF BOOKS, 



MISCELLANEOUS. 

Amateur Mechanic's Workshop. A Treatise containing plain and concise 
directions for the manipulation of Wood and Metals, including Casting, 
Forging, Brazing, Soldering, and Carpentry. By the author of " The 
Lathe and its Uses." 7th ed. Illustrated. 8vo. London, 1888. $3,00 

Hiscox, Gardner D. Compressed Air ; Its Production, Uses, and Appli- 
cations. Comprising the Physical Properties of Air from a Vacuum 
to its Liquid State, its Thermodynamics, Compression, Transmis- 
sion, and Uses as a Motive Power. With 40 Air Tables and 545 
Illustrations. 8vo, cloth. New York, 1901. $5.00 

Half morocco. $6.50 

Plympton, Prof. Geo. W. How to become an Engineer ; or, the Theo- 
retical and Practical Training necessary in fitting for the Duties of 
the Civil Engineer. (Van Nostrand's Science Series). $0.50 

STEAM AND STEAM ENGINES. 

Alexander. Model Engine Construction. With Practical Instructions to 
Artificers and Amateurs. Containing numerous illustrations and twenty- 
one Working Drawings, from Original Drawings by the Author. i2mo. 
London, 1895. ^3-oo 

Baker. Treatise on the Mathematical. Theory of the Steam Engine. 
With Rules at length and Examples worked out, for the use of practical 
men, with numerous diagrams. 8th edition. London, 1890. ^0.60 

Bale. How to Manage a Steam Engine ; a Handbook for all who use 
Steam. Illustrated, with examples of different Types of Engines and 
Boilers ; with Hints on their Construction, Working, Fixing, Economy 
of Fuel, etc. 7th edition. i2mo. London, 1890. $0.80 

Barrus, Geo. H., S.B. Engine Tests; embracing the results of over 
100 Feed- Water Tests and other investigations of various kinds of 
Steam Engines, conducted by the author. Illustrated. 8vo, cloth. 
New York, 1900. $4.00 

Bourne. Catechism of the Steam Engine in its various Applications to 
Mines, Mills, etc. New edition, enlarged. Illustrated. i2mo. New 
York, 1897. $2.oc 

Hand-Book of the Steam Engine, containing all the Rules required 

for the right Construction and Management of Engines of every Class, 
with the easy Arithmetical Solution of those Rules. Illustrated. i2mo 
New York. 1892. |i-75 

Burn. Steam Engine, its History and Mechanism. 3d edition. 8vo, 
Illustrated. London, 1857. $\.fyi 



D. VAN NOSTKAND COMPANY. 

Clark. Steam and the Steam Engine, Stationary and Portable. (Seing 
an Extension of the Elementary Treatise on the Steam Engine, of Mr. 
John Sewell.) 4th edition. London, 1892. $1.40 

The Steam Engine. A Treatise on Steam Engines and Boilers; 

comprising the Principles and Practice of the Combustion of Fuel, the 
Economical Generation of Steam, the Construction of Steam Boilers, 
and the principles, construction, and performance of Steam Engines, 
Stationary, Portable, Locomotive, and Marine, exemplified in Engines 
and Boilers of recent date. Illustrated by above 1,300 figures in the text, 
and a series of folding plates drawn to scale. 2 vols. 8vo. London, 
1895. ^15.00 

Colyer. Treatise on Modern Steam Engines and Boilers, including Land, 
Locomotive, and Marine Engines and Boilers. For the use of Students. 
With 46 plates. 4to. London, 1886. ^5.00 

Cotterill. Steam Engine considered as a Thermodynamic Machine. A 
Treatise on the Thermodynamic Efficiency of Steam Engines. Illus- 
trated by tables, diagrams, and examples from practice. 3d edition, re- 
vised and enlarged. 8vo. London. 1896. net ^4.50 

Diesel. Theory and Construction of a Rational Heat Motor. Translated 
from the German by Bryan Donkin. With eleven figures in the text and 
three plates. 8vo. London, 1894. ^2.50 

Edwards. American Steam Engineer, Theoretical and Practical. With 
Examples of the latest and most approved American Practice on the De- 
sign and Construction of Steam Engines and Boilers of every description. 
For the use of Engineers, Machinists, Boiler Makers, etc. Illustrated by 
77 engravings. i2mo. Philadelphia, 1897. $2.50. 

Practical Steam Engineers' Guide in the Design, Construction, and 

Management of American Stationary, Portable, and Steam Fire Engines, 
Steam Pumps, Boilers, Injectors, Governors, Indicators, Pistons, and 
Rings, Safety Valves and Steam Gauges. For the use of Engineers, 
Firemen, and Steam Users. Illustrated. 3d edition, revised and cor 
rected. i2mo. Philadelphia, 1900. $2.50 

Evers. Steam and other Prime Movers. A Text-Book both Theoretical 
and Practical. Illustrated. i2mo. London, 1890. $i-50 

. Steam and the Steam Engine ; Land, Marine, and Locomotive II 

lustrated. i2mo. New York. ^i.oo 

Ewing. Steam Engine and other Heating Engines. Illustrated. 8vo. 
Cambridge, 1899. ^3-7.5 



LIST OF BOOKS. 

Goodeve. Text-Book on the Steam Engine, With a Supplement on Gas 
Engines and on Heat Engines. 13th edition, enlarged. i2mo. 143 
illustrations. London, 1896. $2,00 

Gould. Arithmetic of the Steam Engine. i2mo, N. Y. 1898. ^i.oo 

Grimshaw. Steam Engine Catechism. A series of direct practical an 
swers to direct practical questions, mainly intended for young engineers 
and for examination questions, nth edition, enlarged and improved. 
i8mo. New York, 1897. ^2.00 

Haeder. Hand-Book on the Steam Engine with especial Reference to 
Small and Medium sized Engines. For the Use of Engine Makers, Me- 
chanical Draughtsmen, Engineering Students, and Users of Steam 
Power. 1,100 illustrations. lamo. London, 1896. $3-00 

Henthorn. Corliss Engine and its Management. Edited by E. P. Watson. 

'3d edition, enlarged with an appendix, by Emil Herter. Illustrated. 

i8mo. New York, 1897. $1.00 

Holmes. Steam Engine. 212 illustrations. lothedition. i2mo. London, 
1900. $2.00 

This is a complete practical and theoretical treatise on the steam-engine, written in 
very clear and beautiful style, rendering the more abstruse principles of the subject as 
plain and simple as it is probably possible to make them. It is one of the best, if not the 
best, combinations of theoretical investigation and practical applications in the whole lite- 
•rature of the subject, and forms an admirable companion to Ripper's smaller and more 
exclusively practical treatise. 

Jamieson. Text-Book of Steam and Steam Engines. 13th edition, 
with numerous Diagrams, four folding Plates, and Examination 
Questions. i2mo. London, 1901. I3.00 

Elementary Manual on Steam and the Steam Engine. With 

numerous Diagrams, Arithmetical Examples, and Examination 
Questions. 8th edition. i2mo. London, 1900. §1.40 

Lardner. Treatise on the Steam Engine, for the Use of Beginners. 
i6th edition. Illustrated. London, 1893. $0.60. 

Le Van. Steam Engine and the Indicator; their Origin and Progres- 
sive Development, including the most recent examples of Steam 
and Gas Motors, together with the Indicator, its Principles, its 
Utility, and its Application. Illustrated by 205 Engravings, chiefly 
of Indicator Cards. 8vo. Philadelphia, 1900. $4.00 

Mallet. Compound Engines. i6mo, boards. New York, 1884. $0.50 

Marks. Relative Proportions of the Steam Engine. Illustrated. 3d edi- 
tion. i2mo. Philadelphia, 1896. $3.00 

Peabody. Table of the Properties of Saturated Steam and other 
Vapors. 6th edition. 8vo. New York, 1901. $1.00 



Z>. VAN NOSTKAND COMPANY. 

Pray. Steam Tables and Engine Constants. For facilitating all calcu- 
lations upon Indicator Diagrams or Various Problems connected with 
the operation of the Steam Engine, from reliable data and with precision 
compiled from Regnault, Rankine, and Dixon directly, making use of the 
exact records. 8vo. New York, 1894. I2.00 

Rankine. Manual of the Steam Engine and other Prime Movers, with 
numerous tables and illustrations. i2mo. 14th edition. London, 1897. 

$5.00 

Rigg. Practical Treatise on the Steam Engine, containing Plans and 
Arrangements of Details for Fixed Steam Engines, with Essays on the 
Principles involved in Design and Construction. Copiously illustrated 
with woodcuts and 96 plates. 4to. 2d edition. New York, 1894. 

^10.00 

Ripper. Steam. Illustrated. i2mo. London, 1889. ^i.oo 

This work is based upon a course of lectures given to an evening class of young me- 
chanical engineers on steam, steam-engines, and boilers. It is remarkably clear, concise^ 
and practical ; no superfluous matter is introduced, and" every page goes directly to the 
point. It is the best book for beginners, and also for those who wish to have a manual 
embracing the practical features of the subjects in small compass. 

Roper. Hand-Book of Modern Steam Fire Engines ; including the run- 
ning, care, and management of Steam Fire Engines and Fire Pumps. 
2d edition, revised and corrected by H. L. Stellwagen. Illustrated. 
i2mo, mor. tucks. Philadelphia, 1897. ^3-50 

Hand-Book of Land and Marine Engines, including the Modelling, 

Construction, Running, and Management of Land and Marine Engines 
and Boilers. 9th edition, revised, enlarged, and improved. i2mo, mor. 
-tucks. Philadelphia, 1897. $3-50' 

" Catechism of High Pressure or Non-Condensing Steam Engines, 

including the Modelling, Constructing, Running, and Management of 
Steam Engines and Steam Boilers. 20th edition, revised and enlarged. 
Illustrated. i2mo, mor. tucks. Philadelphia, 1897. $2.oO' 

. Young Engineer's Own Book. Containing an Explanation of the 

Principle and Theories on which the Steam Engine as a Prime Mover is 
based, with a description of different kinds of Steam Engines, Condens- 
ing and Non-Condensing, Marine, Stationary, Locomotive, Fire, Trac- 
tion, and Portable. 106 illustrations. 3d edition, revised. 16 mo, mor. 
tucks. Philadelphia, 1897. $3.00 

Rose. Modern Steam Engines. An Elementary Treatise upon the 
Steam Engine, written in Plain Language ; for use in the Workshop as 
well as in the Drawing Office. Giving Full Explanations of the Con- 



LIST OF BOOKS. 

struction of Modern Steam Engines; including Diagrams showing their 
Actual Operation ; together with Complete but Simple Explanation of 
the Operations of various kinds of Valves, Valve Motions, and link 
Motions, etc., thereby enabling the ordinary engineer to clearly under- 
stand the Principles involved in their Construction and use, and to Plot 
out their movements upon the Drawing Board. New edition, revised 
and improved. 453 illustrations. 4to. Philadelphia, 1900. $6.00 

Key to Engines and Engine Running. A Practical Treatise upon 

the Management of Steam Engines and Boilers, for the use of those 
who desire to pass an Examination to take Charge of an Engine or 
Boiler. With numerous Illustrations and Instructions upon Engineers' 
Calculations, Indicator Diagrams, Engine Adjustments, and other Valu- 
able Information necessary for Engineers and Firemen. i2mo. N. Y. 
1899. ^2.50 

Thurston. History of the Growth of the Steam Engine. 4th revised 
edition. Illustrated. i2mo. New York, 1897. ^2.50 

Manual of the Steam Engine. For Engineers and Technical 

Schools. Part I, Structure and Theory. Illustrated. 5th edition, 
revised. 8vo. New York, 1900. $6.00 

Part II. Design, Construction, and Operation. Illustrated, 4th edi- 
tion, revised. 8vo. New York, 1900. $6.00 
Or in sets. $10.00 

Hand-Book of Engine and Boiler Trials, and of the Indicator 

and Prony Brake, for Engineers, and Technical Schools. Illustrated. 
4th and revised edition. 8vo. New York, 1897. I5.00 

Stationary Steam Engines, Simple and Compound, especially 



as adapted to Electric Lighting Purposes. 5th edition, revised, with 
additions. Illustrated, i2mo. New York, 1893. $2.50 

TurnbuU. Treatise on the Compound Engine. 2d edition, revised 
and enlarged by Prof. S. W, Robinson. i6mo, boards. New York, 
1884. $0.50 

Watson, E. P. Small Engines and Boilers. A manual of Concise 
and Specific Directions for the Construction of Small Steam Engines 
and Boilers of Modern Types from five Horse-power down to model 
sizes. Illustrated. i2mo, cloth. $1.25 

Weisbach. Heat, Steam, and Steam Engine^ Translated from the 
4th edition of Vol. II. of Weisbach's Mechanics. Containing Notes 
giving practical examples of Stationary, Marine, and Locomotive 
Engines, showing American practice, by R. H. Buel. Numerous 
illustrations. 8vo. New York, 1891. $5.00 



D. VAN NOSTRAND COMPANY 

Whitham. Steam Engine Design. For the use of Mechanical Engi- 
neers, Students, and Draughtsmen. 3d edition, revised. With 210 
illustrations. 8vo. New York, 1902. $5.0Q 



TRANSMISSION OF POWER, BELTING, ETC. 

Kerr, E. W., M. E. Power, and Power Transmission. A Series of 
Lectures delivered to Students, on the Elementary Principles of 
Engineering. Containing numerous full-page Diagrams, Figures 
and Tables. Illustrated. 8vo, cloth. New York, 1902. $2.00 

Toothed Gearing. A Practical Hand-Book for Offices and Workshops. 
By a Foreman Pattern Maker. 184 illustrations. i2mo. London, 
1892. $2.50 

Unwin. On the Development and Transmission of Power from Cen- 
tral Stations. Being the Howard Lectures delivered at the Society 
of Arts in 1893. Illustrated. 8vo, New York, 1894. $3.50 



VALVES AND VALVE GEARS. 

Auchincloss. Practical Application of the Slide-Valve and Link- 
Motion to Stationary, Portable, Locomotive, and Marine Engines, 
with new and simple methods for proportioning the parts. Illus- 
trated. 14th edition, revised and enlarged. 8vo. New York, 
1901. $2.00 

Bankson. Slide Valve Diagrams. A French Method of Obtaining 
Slide Valve Diagrams. 8 Plates. i6mo. New York, 1892. $0.50 

Begtrup, Julius. Slide Valve and its Functions. With special refer- 
ence to modern Practice in the United States. With many Dia- 
grams. Illustrated. 8vo, cloth. $2.00 

Buel. Safety Valves. 3d edition. i6mo, boards. New York, 
1898. $0.50 

Halsey. Slide Valve Gears ; an explanation of the Action and Con- 
struction of plain and cut-oif Slide Valves. Analysis by the Bilgram 
Diagram. 79 illustrations. 7th edition, revised and enlarged. 
i2mo. New York, igoi. $1.50 

' Worm and Spiral Gearing. With Illustrations and Diagrams. 

(Van Nostrand's Science Series, No. 116.) $0.50 



LIST OF BOOKS. 

Le Van. Safety Valves ; Their History, Antecedents, Invention, and 
Calculation. 69 Illustrations. i2mo. New York, 1892. $2.00 

MacCord. Treatise on the Movement of the Eccentric upon the Slide 
Valve, and explaining the Practical Process of Laying out the Move- 
ments, adapting the Valve for its various duties in the Steam Engine, 
for the Use of Engineers, Draughtsmen, Machinists, and Students of 
Valve Motion in general. 2d edition. 4to. Illustrated. New York, 
1883. ^^2.50 

Peabody. Valve Gears and Steam Engines. t,t, Plates. 8vo. New 
York, 1900. $2.50 

Rose. Slide Valve Practically Explained. Embracing Simple and 
Complete Practical Demonstrations of the Operations of each Element 
in a Slide-Valve Movement, and illustrating the effects of variations in 
their proportions, by examples carefully selected from the most *-ecent 
and successful practice. Illustrated. i2mo. Philadelphia, 1895. ^i.oo 

Spangler. Valve Gears. 2d edition, revised and enlarged. 8vo. New 
York, 1900. ^2.50 

Welch. Treatise on a Practical Method of Designing Slide Valve Gear- 
ing by Simple Geometrical Construction, based upon the principles enun- 
ciated in Euclid's Elements, and comprising the various forms of Plain 
Slide Valve and Expansion Gearing; together with Stephenson's, Gooch's, 
and Allen's Link Motions, as applied either to reversing or to variable 
expansion combinations. i2mo. London, 1875. $i-50 

Zeuner. Treatise on Valve Gears, with Special consideration of the link 
motions of locomotive engines. 4th edition. Translated by Prof. J. F. 
Klein, 8vo. London, 1884. ^5.00 



OCT IS 1902 



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